Control body function via lymphocytes

Humoral communication (fluids) in body

Control body function via hormones

Made up of glandular epithelium -> secretes product

Substances (hormones) cross to adjacent
cell via gap junctions

Substance crosses to other cells by
diffusion through interstitial fluid

Substance affects secreting cell itself

Substances (hormones) cross to adjacent
cell via gap junctions

Substance crosses to other cells by
diffusion through interstitial fluid

Substance affects secreting cell itself

Substances (hormones) cross to adjacent
cell via gap junctions

Substance crosses to other cells by
diffusion through interstitial fluid

Substance affects secreting cell itself

Neurons secrete chemicals as hormones into blood instead of as neurotransmitters at
synapse
Endocrine system works closely with nervous system

Product goes through duct (simple cuboidal
epithelium) outside of the body
• e.g. Sweat, sebaceous, digestive,
mammary glands

Secretes hormone into the blood
Ductless
Hormone travels in blood to target tissue
which has receptors for that hormone
Example: Pineal, pituitary, pancreas,
ovaries, testes, adrenal, and thyroid

Neurons secrete chemicals as hormones into blood instead of as neurotransmitters at
synapse
Endocrine system works closely with nervous system

Product goes through duct (simple cuboidal
epithelium) outside of the body
e.g. Sweat, sebaceous, digestive,
mammary glands

Secretes hormone into the blood
Ductless
Hormone travels in blood to target tissue
which has receptors for that hormone
Example: Pineal, pituitary, pancreas,
ovaries, testes, adrenal, and thyroid

Neurons secrete chemicals as hormones into blood instead of as neurotransmitters at
synapse
Endocrine system works closely with nervous system

Product goes through duct (simple cuboidal
epithelium) outside of the body
e.g. Sweat, sebaceous, digestive,
mammary glands

Secretes hormone into the blood
Ductless
Hormone travels in blood to target tissue
which has receptors for that hormone
Example: Pineal, pituitary, pancreas,
ovaries, testes, adrenal, and thyroid

Chemical regulator (molecules) that will target a gland to stimulate specific cells or tissues into action

(hypothalamus)
Short chains of amino acids are peptides, long chains are proteins

Based on amino acid tyrosine
Includes thyroid hormones and catecholamines (epinephrine, norepinephrine and dopamine)

Cholesterol backbone w/side chains
Adrenal cortex and gonads (sex steroids)

Prostaglandins – derived from arachidonic acid

Chemical regulator (molecules) that will target a gland to stimulate specific cells or tissues into action

(hypothalamus)
Short chains of amino acids are peptides, long chains are proteins

Based on amino acid tyrosine
Includes thyroid hormones and catecholamines (epinephrine, norepinephrine and dopamine)

Cholesterol backbone w/side chains
Adrenal cortex and gonads (sex steroids)

Prostaglandins – derived from arachidonic acid

Chemical regulator (molecules) that will target a gland to stimulate specific cells or tissues into action

(hypothalamus)
Short chains of amino acids are peptides, long chains are proteins

Based on amino acid tyrosine
Includes thyroid hormones and catecholamines (epinephrine, norepinephrine and dopamine)

Cholesterol backbone w/side chains
Adrenal cortex and gonads (sex steroids)

Prostaglandins – derived from arachidonic acid

Chemical regulator (molecules) that will target a gland to stimulate specific cells or tissues into action

(hypothalamus)
Short chains of amino acids are peptides, long chains are proteins

Based on amino acid tyrosine
Includes thyroid hormones and catecholamines (epinephrine, norepinephrine and dopamine)

Cholesterol backbone w/side chains
Adrenal cortex and gonads (sex steroids)

Prostaglandins – derived from arachidonic acid

Chemical regulator (molecules) that will target a gland to stimulate specific cells or tissues into action

(hypothalamus)
Short chains of amino acids are peptides, long chains are proteins

Based on amino acid tyrosine
Includes thyroid hormones and catecholamines (epinephrine, norepinephrine and dopamine)

Cholesterol backbone w/side chains
Adrenal cortex and gonads (sex steroids)

Prostaglandins – derived from arachidonic acid

Rare

When a hormone is produced it
stimulates more hormone to be produced
(oxytocin)

Common

When a hormone produced causes a
decrease in production.

When a hormone from a different
endocrine gland causes or inhibits the
release of a specific hormone

Rare

When a hormone is produced it
stimulates more hormone to be produced
(oxytocin)

Common

When a hormone produced causes a
decrease in production.

When a hormone from a different
endocrine gland causes or inhibits the
release of a specific hormone

Rare

When a hormone is produced it
stimulates more hormone to be produced
(oxytocin)

Common

When a hormone produced causes a
decrease in production.

When a hormone from a different
endocrine gland causes or inhibits the
release of a specific hormone

“Master gland”
Two distinct parts
1. The anterior lobe (anterior pituitary;
adenohypophysis)
2. The posterior lobe (posterior pituitary;
neurohypophysis).

Nerve tissue with ends of axons of
neurons with somas in nuclei in
hypothalamus
Axons terminate on capillaries

Stimulus for release: increased blood
sodium concentration from
dehydration
Target: kidney tubules
Effect: increased water resorption ->
decreased urine volume, also
increases blood pressure

Stimulus: neuroendocrine reflex of

suckling, cervical stimulation

Target: myoepithelial cells of

mammary gland, smooth muscle in

uterus

Effect: milk letdown, uterine

contraction

Stimulus: neuroendocrine reflex of
suckling, cervical stimulation
Target: kidney tubules
Effect: increased water resorption ->
decreased urine volume, also
increases blood pressure

“Master gland”
Two distinct parts
1. The anterior lobe (anterior pituitary;
adenohypophysis)
2. The posterior lobe (posterior pituitary;
neurohypophysis).

Nerve tissue with ends of axons of
neurons with somas in nuclei in
hypothalamus
Axons terminate on capillaries

Stimulus for release: increased blood
sodium concentration from
dehydration
Target: kidney tubules
Effect: increased water resorption ->
decreased urine volume, also
increases blood pressure

Stimulus: neuroendocrine reflex of

suckling, cervical stimulation

Target: myoepithelial cells of

mammary gland, smooth muscle in

uterus

Effect: milk letdown, uterine

contraction

Stimulus: neuroendocrine reflex of
suckling, cervical stimulation
Target: kidney tubules
Effect: increased water resorption ->
decreased urine volume, also
increases blood pressure

“Master gland”
Two distinct parts
1. The anterior lobe (anterior pituitary;
adenohypophysis)
2. The posterior lobe (posterior pituitary;
neurohypophysis).

Nerve tissue with ends of axons of
neurons with somas in nuclei in
hypothalamus
Axons terminate on capillaries

Stimulus for release: increased blood
sodium concentration from
dehydration
Target: kidney tubules
Effect: increased water resorption ->
decreased urine volume, also
increases blood pressure

Stimulus: neuroendocrine reflex of

suckling, cervical stimulation

Target: myoepithelial cells of

mammary gland, smooth muscle in

uterus

Effect: milk letdown, uterine

contraction

Stimulus: neuroendocrine reflex of
suckling, cervical stimulation
Target: kidney tubules
Effect: increased water resorption ->
decreased urine volume, also
increases blood pressure

“Master gland”
Two distinct parts
1. The anterior lobe (anterior pituitary;
adenohypophysis)
2. The posterior lobe (posterior pituitary;
neurohypophysis).

Nerve tissue with ends of axons of
neurons with somas in nuclei in
hypothalamus
Axons terminate on capillaries

Stimulus for release: increased blood
sodium concentration from
dehydration
Target: kidney tubules
Effect: increased water resorption ->
decreased urine volume, also
increases blood pressure

Stimulus: neuroendocrine reflex of

suckling, cervical stimulation

Target: myoepithelial cells of

mammary gland, smooth muscle in

uterus

Effect: milk letdown, uterine

contraction

Stimulus: neuroendocrine reflex of
suckling, cervical stimulation
Target: kidney tubules
Effect: increased water resorption ->
decreased urine volume, also
increases blood pressure

Pars distalis - Largest Part

Pars intermedia—between pars distalis and
pars nervosa

Pars tuberalis—around stalk connecting to
brain

Pars tuberalis—between pars distalis and
pars nervosa

Pars distalis—around stalk connecting to
brain

Growth hormones

Adrenocorticotropic hormone (ACTH)

(Lactotropes): prolactin

Thyroid stimulating hormone (TSH)

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Growth hormones

Adrenocorticotropic hormone (ACTH)

(Lactotropes): prolactin

Thyroid stimulating hormone (TSH)

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Growth hormones

Adrenocorticotropic hormone (ACTH)

(Lactotropes): prolactin

Thyroid stimulating hormone (TSH)

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Growth hormones

Adrenocorticotropic hormone (ACTH)

(Lactotropes): prolactin

Thyroid stimulating hormone (TSH)

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Growth hormones

Adrenocorticotropic hormone (ACTH)

(Lactotropes): prolactin

Thyroid stimulating hormone (TSH)

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Target: many body cells, especially bone and muscle
More in young animals
Effects:
Hypertrophy and hyperplasia
Metabolism: increased protein synthesis, increased fatty acid
mobilization, decreased glucose uptake
Control: GHRH (releasing) and GHIH (inhibiting)/Somatostatin from
hypothalamus

Stimulate gonads

gonadotropin releasing hormone (GnRH) from
hypothalamus

Involved w/ovulation and
corpus luteum (CL) formation  targets ova to bring on
ovulation
Also stimulates testes to produce testosterone in males

Involved w/ follicular
development and ovulation
Also has roles in sperm development in males

Target: many body cells, especially bone and muscle
More in young animals
Effects:
Hypertrophy and hyperplasia
Metabolism: increased protein synthesis, increased fatty acid
mobilization, decreased glucose uptake
Control: GHRH (releasing) and GHIH (inhibiting)/Somatostatin from
hypothalamus

Stimulate gonads

gonadotropin releasing hormone (GnRH) from
hypothalamus

Involved w/ovulation and
corpus luteum (CL) formation  targets ova to bring on
ovulation
Also stimulates testes to produce testosterone in males

Involved w/ follicular
development and ovulation
Also has roles in sperm development in males

Target: many body cells, especially bone and muscle
More in young animals
Effects:
Hypertrophy and hyperplasia
Metabolism: increased protein synthesis, increased fatty acid
mobilization, decreased glucose uptake
Control: GHRH (releasing) and GHIH (inhibiting)/Somatostatin from
hypothalamus

Stimulate gonads

gonadotropin releasing hormone (GnRH) from
hypothalamus

Involved w/ovulation and
corpus luteum (CL) formation  targets ova to bring on
ovulation
Also stimulates testes to produce testosterone in males

Involved w/ follicular
development and ovulation
Also has roles in sperm development in males

Target: many body cells, especially bone and muscle
More in young animals
Effects:
Hypertrophy and hyperplasia
Metabolism: increased protein synthesis, increased fatty acid
mobilization, decreased glucose uptake
Control: GHRH (releasing) and GHIH (inhibiting)/Somatostatin from
hypothalamus

Stimulate gonads

gonadotropin releasing hormone (GnRH) from
hypothalamus

Involved w/ovulation and
corpus luteum (CL) formation  targets ova to bring on
ovulation
Also stimulates testes to produce testosterone in males

Involved w/ follicular
development and ovulation
Also has roles in sperm development in males

Targets mammary cells to increase lactation

Note: this is milk production, NOT milk ejection, which is

controlled by oxytocin

Controlled by many things, including dopamine

Thyrotropin
Stimulates thyroid gland to release its hormones
Controlled by thyrotropin releasing hormone from
hypothalamus and by cold, stress, etc.

Large precursor molecule can form several hormones

Targets mammary cells to increase lactation

Note: this is milk production, NOT milk ejection, which is

controlled by oxytocin

Controlled by many things, including dopamine

Thyrotropin
Stimulates thyroid gland to release its hormones
Controlled by thyrotropin releasing hormone from
hypothalamus and by cold, stress, etc.

Large precursor molecule can form several hormones

Targets mammary cells to increase lactation

Note: this is milk production, NOT milk ejection, which is

controlled by oxytocin

Controlled by many things, including dopamine

Thyrotropin
Stimulates thyroid gland to release its hormones
Controlled by thyrotropin releasing hormone from
hypothalamus and by cold, stress, etc.

Large precursor molecule can form several hormones

Stimulates adrenal cortex to release its
hormones

Then converted to beta-endorphin (B-EP)
Natural pain reliever

Pigment movement and color changes,
especially in amphibians and reptiles

Stimulates adrenal cortex to release its
hormones

Then converted to beta-endorphin (B-EP)
Natural pain reliever

Pigment movement and color changes,
especially in amphibians and reptiles

Stimulates adrenal cortex to release its
hormones

Then converted to beta-endorphin (B-EP)
Natural pain reliever

Pigment movement and color changes,
especially in amphibians and reptiles

Produces melatonin
Involved with light/dark cycles
Sleep/wake
Seasonal breeding
Nocturnal activity

Location and structure: neck near larynx
Bilobed-two lobes
Microscopically: cells arranged in follicles with space
filled with thyroglobulin (storage of thyroid hormone)
Stored as colloid  stains pink
“C” or parafollicular cells between follicle

From “C” cells
Decreases blood calcium

Produces melatonin
Involved with light/dark cycles
Sleep/wake
Seasonal breeding
Nocturnal activity

Location and structure: neck near larynx
Bilobed-two lobes
Microscopically: cells arranged in follicles with space
filled with thyroglobulin (storage of thyroid hormone)
Stored as colloid  stains pink
“C” or parafollicular cells between follicle

From “C” cells
Decreases blood calcium

Produces melatonin
Involved with light/dark cycles
Sleep/wake
Seasonal breeding
Nocturnal activity

Location and structure: neck near larynx
Bilobed-two lobes
Microscopically: cells arranged in follicles with space
filled with thyroglobulin (storage of thyroid hormone)
Stored as colloid  stains pink
“C” or parafollicular cells between follicle

From “C” cells
Decreases blood calcium

Iodinated conjugate of amino acid tyrosine
T4 -> T3 (active version)
Carried in blood bound to thyroid binding
globulin (TBG)—”bound” vs. “free”, “total”

From
hypothalamus

From adenohypophysis-anterior pituitary
gland
Stress, temperature, other hormones
Negative feedback of T3/T4 on thyroid,
adenohypophysis and hypothalamus

Iodinated conjugate of amino acid tyrosine
T4 -> T3 (active version)
Carried in blood bound to thyroid binding
globulin (TBG)—”bound” vs. “free”, “total”

From
hypothalamus

From adenohypophysis-anterior pituitary
gland
Stress, temperature, other hormones
Negative feedback of T3/T4 on thyroid,
adenohypophysis and hypothalamus

Iodinated conjugate of amino acid tyrosine
T4 -> T3 (active version)
Carried in blood bound to thyroid binding
globulin (TBG)—”bound” vs. “free”, “total”

From
hypothalamus

From adenohypophysis-anterior pituitary
gland
Stress, temperature, other hormones
Negative feedback of T3/T4 on thyroid,
adenohypophysis and hypothalamus

Target organs: “all” cells
Increase BMR (basal metabolic rate)
“Permissive” effect on many organ
systems
e.g., reproduction, skin, growth

Increased cardiac output

Increases blood glucose by:
Increased carbohydrate uptake from
GIT

Increases blood glucose by

Increased gluconeogenesis
Increased glycolysis
Increased oxidation of fatty acids

Increased gluconeogenesis
Decreased glycolysis
Increased oxidation of fatty acids

Increased cardiac output

Decreases blood glucose by:
Increased carbohydrate uptake from
GIT

Small glands embedded in thyroid or
nearby
Produce parathyroid hormone (PTH)
Increases blood serum calcium

Cranial to kidney

Outer portion
Has zones
Produces corticosteroids

Sympathetic nerve ganglion
Produces catecholamines

Small glands embedded in thyroid or
nearby
Produce parathyroid hormone (PTH)
Increases blood serum calcium

Cranial to kidney

Outer portion
Has zones
Produces corticosteroids

Sympathetic nerve ganglion
Produces catecholamines

Caudal to Kidney

Small glands embedded in thyroid or
nearby
Produce parathyroid hormone (PTH)
Increases blood serum calcium

Cranial to kidney

Outer portion
Has zones
Produces corticosteroids

Sympathetic nerve ganglion
Produces catecholamines

Caudal to Kidney

Small glands embedded in thyroid or
nearby
Produce parathyroid hormone (PTH)
Increases blood serum calcium

Cranial to kidney

Outer portion
Has zones
Produces corticosteroids

Sympathetic nerve ganglion
Produces catecholamines

Caudal to Kidney

Cortisol, corticosterone
Increase blood glucose
Targets muscles/tissues

Corticotropin-
releasing hormone (CRH)

Adrenocorticotropic hormone (ACTH)

Cortisol

Cortisol, corticosterone
Increase blood glucose
Targets muscles/tissues

Corticotropin-
releasing hormone (CRH)

Adrenocorticotropic hormone (ACTH)

Cortisol

Cortisol, corticosterone
Increase blood glucose
Targets muscles/tissues

Corticotropin-
releasing hormone (CRH)

Adrenocorticotropic hormone (ACTH)

Cortisol

Cortisol, corticosterone
Increase blood glucose
Targets muscles/tissues

Corticotropin-
releasing hormone (CRH)

Adrenocorticotropic hormone (ACTH)

Cortisol

Mostly aldosterone
Acts on kidneys to increase sodium
retention and water retention in blood out
of urine, decreased urine volume
Control:
Slightly by ACTH
Mostly by increased plasma osmolarity
(increased sodium, dehydration)

Adrenal gland
hormones
Catecholamines
Epinephrine, norepinephrine, dopamine
Short term stress response (fight or flight)
Control: sympathetic nerve stimulation
Target: viscera, heart, blood vessels,
gastrointestinal tract (GIT), many cells

Diffuse gland in first loop of small intestine
(duodenum)

(most of gland)
Digestive enzymes, mucus and bicarbonate

Islets of Langerhans

Mostly aldosterone
Acts on kidneys to increase sodium
retention and water retention in blood out
of urine, decreased urine volume
Control:
Slightly by ACTH
Mostly by increased plasma osmolarity
(increased sodium, dehydration)

Adrenal gland
hormones
Catecholamines
Epinephrine, norepinephrine, dopamine
Short term stress response (fight or flight)
Control: sympathetic nerve stimulation
Target: viscera, heart, blood vessels,
gastrointestinal tract (GIT), many cells

Diffuse gland in first loop of small intestine
(duodenum)

(most of gland)
Digestive enzymes, mucus and bicarbonate

Islets of Langerhans

Mostly aldosterone
Acts on kidneys to increase sodium
retention and water retention in blood out
of urine, decreased urine volume
Control:
Slightly by ACTH
Mostly by increased plasma osmolarity
(increased sodium, dehydration)

Adrenal gland
hormones
Catecholamines
Epinephrine, norepinephrine, dopamine
Short term stress response (fight or flight)
Control: sympathetic nerve stimulation
Target: viscera, heart, blood vessels,
gastrointestinal tract (GIT), many cells

Diffuse gland in first loop of small intestine
(duodenum)

(most of gland)
Digestive enzymes, mucus and bicarbonate

Islets of Langerhans

Mostly aldosterone
Acts on kidneys to increase sodium
retention and water retention in blood out
of urine, decreased urine volume
Control:
Slightly by ACTH
Mostly by increased plasma osmolarity
(increased sodium, dehydration)

Adrenal gland
hormones
Catecholamines
Epinephrine, norepinephrine, dopamine
Short term stress response (fight or flight)
Control: sympathetic nerve stimulation
Target: viscera, heart, blood vessels,
gastrointestinal tract (GIT), many cells

Diffuse gland in first loop of small intestine
(duodenum)

(most of gland)
Digestive enzymes, mucus and bicarbonate

Islets of Langerhans

Mostly aldosterone
Acts on kidneys to increase sodium
retention and water retention in blood out
of urine, decreased urine volume
Control:
Slightly by ACTH
Mostly by increased plasma osmolarity
(increased sodium, dehydration)

Adrenal gland
hormones
Catecholamines
Epinephrine, norepinephrine, dopamine
Short term stress response (fight or flight)
Control: sympathetic nerve stimulation
Target: viscera, heart, blood vessels,
gastrointestinal tract (GIT), many cells

Diffuse gland in first loop of small intestine
(duodenum)

(most of gland)
Digestive enzymes, mucus and bicarbonate

Islets of Langerhans

Increase heart rate
Increase blood pressure
Stimulate ACTH production

Decrease GIT activity
Increase blood glucose

Increase GIT activity
Decrease blood glucose

Decrease heart rate
Decrease blood pressure
Stimulate ACTH production

Released from beta cells
Stimulated by increased blood glucose
Targets: liver, adipose, muscle
Effects: decreases blood glucose by:
Glycogenesis
Increased cellular uptake from blood

From alpha cells
Stimulated by decreased blood glucose
Targets: same as insulin
Effects: increases blood glucose by:
Gluconeogenesis
Glycogenolysis

From delta cells
Inhibits both alpha and beta cells

Released from beta cells
Stimulated by increased blood glucose
Targets: liver, adipose, muscle
Effects: decreases blood glucose by:
Glycogenesis
Increased cellular uptake from blood

From alpha cells
Stimulated by decreased blood glucose
Targets: same as insulin
Effects: increases blood glucose by:
Gluconeogenesis
Glycogenolysis

From delta cells
Inhibits both alpha and beta cells

Released from beta cells
Stimulated by increased blood glucose
Targets: liver, adipose, muscle
Effects: decreases blood glucose by:
Glycogenesis
Increased cellular uptake from blood

From alpha cells
Stimulated by decreased blood glucose
Targets: same as insulin
Effects: increases blood glucose by:
Gluconeogenesis
Glycogenolysis

From delta cells
Inhibits both alpha and beta cells

Between seminiferous tubules
Produce testosterone
Stimulated by LH from anterior
pituitary

Support cell involved in sperm
production, stimulated by FSH

Follicular organ
Tunica albuginea on outside:
fibrous C.T.
Follicles of different stages
throughout
Primary, secondary, tertiary
Graafian/mature

Between seminiferous tubules
Produce testosterone
Stimulated by LH from anterior
pituitary

Support cell involved in sperm
production, stimulated by FSH

Follicular organ
Tunica albuginea on outside:
fibrous C.T.
Follicles of different stages
throughout
Primary, secondary, tertiary
Graafian/mature

Between seminiferous tubules
Produce testosterone
Stimulated by LH from anterior
pituitary

Support cell involved in sperm
production, stimulated by FSH

Follicular organ
Tunica albuginea on outside:
fibrous C.T.
Follicles of different stages
throughout
Primary, secondary, tertiary
Graafian/mature

The formation of sperm

Deposition of the sperm into the female

Sperm are
produced in the seminiferous
tubules of the testes and are then
transported through the rete testes
to the epididymis, where they are
stored and matured.

Actual Transport of semen through the penile urethra to the region of the cervix or into the uterus of the female

Convoluted
and occupy the greatest portion of each
testicle -> produce spermatozoa

Connective tissue capsule
that surrounds the testicle.
Deep to tunica vaginalis

The formation of sperm

Deposition of the sperm into the female

Sperm are
produced in the seminiferous
tubules of the testes and are then
transported through the rete testes
to the epididymis, where they are
stored and matured.

Actual Transport of semen through the penile urethra to the region of the cervix or into the uterus of the female

Convoluted
and occupy the greatest portion of each
testicle -> produce spermatozoa

Connective tissue capsule
that surrounds the testicle.
Deep to tunica vaginalis

The formation of sperm

Deposition of the sperm into the female

Sperm are
produced in the seminiferous
tubules of the testes and are then
transported through the rete testes
to the epididymis, where they are
stored and matured.

Actual Transport of semen through the penile urethra to the region of the cervix or into the uterus of the female

Convoluted
and occupy the greatest portion of each
testicle -> produce spermatozoa

Connective tissue capsule
that surrounds the testicle.
Deep to tunica vaginalis

The formation of sperm

Deposition of the sperm into the female

Sperm are
produced in the seminiferous
tubules of the testes and are then
transported through the rete testes
to the epididymis, where they are
stored and matured.

Actual Transport of semen through the penile urethra to the region of the cervix or into the uterus of the female

Convoluted
and occupy the greatest portion of each
testicle -> produce spermatozoa

Connective tissue capsule
that surrounds the testicle.
Deep to tunica vaginalis

The formation of sperm

Deposition of the sperm into the female

Sperm are
produced in the seminiferous
tubules of the testes and are then
transported through the rete testes
to the epididymis, where they are
stored and matured.

Actual Transport of semen through the penile urethra to the region of the cervix or into the uterus of the female

Convoluted
and occupy the greatest portion of each
testicle -> produce spermatozoa

Connective tissue capsule
that surrounds the testicle.
Deep to tunica vaginalis

Sertoli Cells

Myoid Cells

(The intratesticular network of
straight tubules that receives content from the
convoluted seminiferous tubules)

Found in the connective tissue surrounding the seminiferous tubules, responsible for testosterone production

Sertoli Cells

Myoid Cells

(The intratesticular network of
straight tubules that receives content from the
convoluted seminiferous tubules)

Found in the connective tissue surrounding the seminiferous tubules, responsible for testosterone production

Sertoli Cells

Myoid Cells

(The intratesticular network of
straight tubules that receives content from the
convoluted seminiferous tubules)

Found in the connective tissue surrounding the seminiferous tubules, responsible for testosterone production

Sertoli Cells

Myoid Cells

(The intratesticular network of
straight tubules that receives content from the
convoluted seminiferous tubules)

Found in the connective tissue surrounding the seminiferous tubules, responsible for testosterone production

Sustentacular (supporting)
cells.
Provides a “nurse” function
for developing spermatozoa.

Processes from Sertoli cells
surround spermatids and
spermatocytes and provide
intimate contact with all
stages of Metal-zoa
production

Processes from Sertoli cells
surround spermatids and
spermatocytes and provide
intimate contact with all
stages of spermatozoa
production

The basal junction (tight
junction) with adjacent Sertoli
cells forms a blood–testis barrier

Prevents spermatozoa from entering the interstitium

Sustentacular (supporting)
cells.
Provides a “nurse” function
for developing eggs

Head, body and tail
The head of the epididymis receives sperm
and fluid through efferent ducts from the rete
testis

Spermatozoa are moved to the epididymis by
the flow of fluid into the lumen of the
seminiferous tubules
Storage in the epididymis allows the
spermatozoa to reach maturity and become
motile.

Reabsorption of much of the seminiferous
tubular fluid occurs in the head of the
epididymis.

Reabsorption of much of the seminiferous
interstitial fluid occurs in the head of the
epididymis.

Head, body and tail
The head of the epididymis receives egg
and fluid through efferent ducts from the rete
testis

The
continuation of the duct system from the tail
of the epididymis to the pelvic urethra

Vas deferens enclosed
along with the testicular artery, vein, nerve,
and lymphatic vessels

Passes through the
inguinal rings

Enlarged, glandular area (variable size among species)

Fibrous connection to the scrotum

The
continuation of the duct system from the tail
of the epididymis to the pelvic urethra

Vas deferens enclosed
along with the testicular artery, vein, nerve,
and lymphatic vessels

Passes through the
inguinal rings

Enlarged, glandular area (variable size among species)

Fibrous connection to the scrotum

The
continuation of the duct system from the tail
of the epididymis to the pelvic urethra

Vas deferens enclosed
along with the testicular artery, vein, nerve,
and lymphatic vessels

Passes through the
inguinal rings

Enlarged, glandular area (variable size among species)

Fibrous connection to the scrotum

The
continuation of the duct system from the tail
of the epididymis to the pelvic urethra

Vas deferens enclosed
along with the testicular artery, vein, nerve,
and lymphatic vessels

Passes through the
inguinal rings

Enlarged, glandular area (variable size among species)

Fibrous connection to the scrotum

During embryonic development, the
testes are intraabdominal but
outside the peritoneum

As development and growth
progress, the gubernaculum testis
“pulls” the testes through the
inguinal canal into the scrotum that creates a double-walled tube of peritoneum

The proper ligament of testis and ligament of tail of epididymis are remnant of gubernaculum

The testis, epididymis, ductus
deferens, and testicular vessels,
nerves, and lymphatics are
enveloped by the inner tube of
peritoneum known as the visceral
vaginal tunic.

The ovaries, epididymis, ductus
deferens, and testicular vessels,
nerves, and lymphatics are
enveloped by the inner tube of
peritoneum known as the visceral
vaginal tunic.

As development and growth
progress, the gubernaculum testis
“stretches” the testes through the
inguinal canal into the scrotum that creates a double-walled tube of peritoneum

The proper ligament of testis and ligament of tail of epididymis are remnant of gubernaculum

The outer tube of peritoneum
and lines the scrotum

The vessels, nerves, lymphatics, and
ductus deferens

An extension of the internal abdominal oblique muscle

Lies on the spermatic cord and assists with drawing the testes closer to the abdominal wall

Important for temperature regulation

The outer tube of peritoneum
and lines the scrotum

The vessels, nerves, lymphatics, and
ductus deferens

An extension of the internal abdominal oblique muscle

Lies on the spermatic cord and assists with drawing the testes closer to the abdominal wall

Important for temperature regulation

The outer tube of peritoneum
and lines the scrotum

The vessels, nerves, lymphatics, and
ductus deferens

An extension of the internal abdominal oblique muscle

Lies on the spermatic cord and assists with drawing the testes closer to the abdominal wall

Important for temperature regulation

Enlargements of the terminal part
of the ductus deferens, and their
secretion empties into the lumens
of the ductus deferens – reservoir
for sperm

Paired glands that empty into the
pelvic urethra along with the
ductus deferens

Encircling the urethra.
Multiple ducts empty directly into

The paired glands are the most caudal of the accessory glands

At the time of ejaculation, the accessory sex gland secretions are mixed with sperm and fluid from the epididymis to form semen

Enlargements of the terminal part
of the ductus deferens, and their
secretion empties into the lumens
of the ductus deferens – reservoir
for sperm

Paired glands that empty into the
pelvic urethra along with the
ductus deferens

Encircling the urethra.
Multiple ducts empty directly into

The paired glands are the most caudal of the accessory glands

At the time of ejaculation, the accessory sex gland secretions are mixed with sperm and fluid from the epididymis to form semen

Enlargements of the terminal part
of the ductus deferens, and their
secretion empties into the lumens
of the ductus deferens – reservoir
for sperm

Paired glands that empty into the
pelvic urethra along with the
ductus deferens

Encircling the urethra.
Multiple ducts empty directly into

The paired glands are the most caudal of the accessory glands

At the time of ejaculation, the accessory sex gland secretions are mixed with sperm and fluid from the epididymis to form semen

Enlargements of the terminal part
of the ductus deferens, and their
secretion empties into the lumens
of the ductus deferens – reservoir
for sperm

Paired glands that empty into the
pelvic urethra along with the
ductus deferens

Encircling the urethra.
Multiple ducts empty directly into

The paired glands are the most caudal of the accessory glands

At the time of ejaculation, the accessory sex gland secretions are mixed with sperm and fluid from the epididymis to form semen

Enlargements of the terminal part
of the ductus deferens, and their
secretion empties into the lumens
of the ductus deferens – reservoir
for sperm

Paired glands that empty into the
pelvic urethra along with the
ductus deferens

Encircling the urethra.
Multiple ducts empty directly into

The paired glands are the most caudal of the accessory glands

At the time of ejaculation, the accessory sex gland secretions are mixed with sperm and fluid from the epididymis to form semen

Organ of copulation
through which urine and
semen pass by way of the
penile urethra

The
penis begin at the caudal
border of the pelvic ischial arch

The forward extension from the roots

+ Free extremity

Organ of copulation
through which urine and
semen pass by way of the
penile urethra

The
penis begin at the caudal
border of the pelvic ischial arch

The forward extension from the roots

+ Free extremity

Organ of copulation
through which urine and
semen pass by way of the
penile urethra

The
penis begin at the caudal
border of the pelvic ischial arch

The forward extension from the roots

+ Free extremity

The internal structure is occupied
mostly by cavernous tissue that fills
with blood during erection

Dense fibroelastic covering surrounds the corpus
cavernosum and also contributes to
the connective tissue sheets found
within it.

More cavernous space and less
connective tissue
Characteristic of the horse and dog
During erection the
musculocavernous penis greatly
increases in both length and width
as the cavernous spaces fill with
blood

Less cavernous space and more connective tissue

Fibroelastic penis is found in the ruminant (Cattle, sheep, goat) and pig

Increase in length is largely brought about by a straightening of the sigmoid flexure

The internal structure is occupied
mostly by cavernous tissue that fills
with blood during erection

Dense fibroelastic covering surrounds the corpus
cavernosum and also contributes to
the connective tissue sheets found
within it.

More cavernous space and less
connective tissue
Characteristic of the horse and dog
During erection the
musculocavernous penis greatly
increases in both length and width
as the cavernous spaces fill with
blood

Less cavernous space and more connective tissue

Fibroelastic penis is found in the ruminant (Cattle, sheep, goat) and pig

Increase in length is largely brought about by a straightening of the sigmoid flexure

The internal structure is occupied
mostly by cavernous tissue that fills
with blood during erection

Dense fibroelastic covering surrounds the corpus
cavernosum and also contributes to
the connective tissue sheets found
within it.

More cavernous space and less
connective tissue
Characteristic of the horse and dog
During erection the
musculocavernous penis greatly
increases in both length and width
as the cavernous spaces fill with
blood

Less cavernous space and more connective tissue

Fibroelastic penis is found in the ruminant (Cattle, sheep, goat) and pig

Increase in length is largely brought about by a straightening of the sigmoid flexure

The internal structure is occupied
mostly by cavernous tissue that fills
with blood during erection

Dense fibroelastic covering surrounds the corpus
cavernosum and also contributes to
the connective tissue sheets found
within it.

More cavernous space and less
connective tissue
Characteristic of the horse and dog
During erection the
musculocavernous penis greatly
increases in both length and width
as the cavernous spaces fill with
blood

Less cavernous space and more connective tissue

Fibroelastic penis is found in the ruminant (Cattle, sheep, goat) and pig

Increase in length is largely brought about by a straightening of the sigmoid flexure

Bull, ram, and boar have it

Resulting in an S shape when not erect

Erection causes extension of the flexure

An invaginated fold of
skin that surrounds the
free extremity of the
penis
The stallion has a
double-folded prepuce

The boar has a preputial diverticulum (pouch) on the dorsal wall, which often contains decomposing urine and macerated epithelium

Low testosterone stimulates
anterior pituitary  releases LH
luteinizing hormone  stimulates
Leydig cells to make testosterone
Presence of testosterone inhibits
the further secretion of LH and
testosterone levels are thus
stabilized.
A negative feedback system.
Within the seminiferous tubules,
testosterone maintains
spermatogenesis

Anterior pituitary, releases follicle
stimulating hormone (FSH) -> promotes support of sperm cells

Produce a hormone known as inhibin -> inhibits secretion of FSH by the anterior pituitary (negative feedback loop)

Bull, ram, and boar have it

Resulting in an S shape when not erect

Erection causes extension of the flexure

An invaginated fold of
skin that surrounds the
free extremity of the
penis
The stallion has a
double-folded prepuce

The boar has a preputial diverticulum (pouch) on the dorsal wall, which often contains decomposing urine and macerated epithelium

Low testosterone stimulates
anterior pituitary  releases LH
luteinizing hormone  stimulates
Leydig cells to make testosterone
Presence of testosterone inhibits
the further secretion of LH and
testosterone levels are thus
stabilized.
A negative feedback system.
Within the seminiferous tubules,
testosterone maintains
spermatogenesis

Anterior pituitary, releases follicle
stimulating hormone (FSH) -> promotes support of sperm cells

Produce a hormone known as inhibin -> inhibits secretion of FSH by the anterior pituitary (negative feedback loop)

Bull, ram, and boar have it

Resulting in an S shape when not erect

Erection causes extension of the flexure

An invaginated fold of
skin that surrounds the
free extremity of the
penis
The stallion has a
double-folded prepuce

The boar has a preputial diverticulum (pouch) on the dorsal wall, which often contains decomposing urine and macerated epithelium

Low testosterone stimulates
anterior pituitary  releases LH
luteinizing hormone  stimulates
Leydig cells to make testosterone
Presence of testosterone inhibits
the further secretion of LH and
testosterone levels are thus
stabilized.
A negative feedback system.
Within the seminiferous tubules,
testosterone maintains
spermatogenesis

Anterior pituitary, releases follicle
stimulating hormone (FSH) -> promotes support of sperm cells

Produce a hormone known as inhibin -> inhibits secretion of FSH by the anterior pituitary (negative feedback loop)

Bull, ram, and boar have it

Resulting in an S shape when not erect

Erection causes extension of the flexure

An invaginated fold of
skin that surrounds the
free extremity of the
penis
The stallion has a
double-folded prepuce

The boar has a preputial diverticulum (pouch) on the dorsal wall, which often contains decomposing urine and macerated epithelium

Low testosterone stimulates
anterior pituitary  releases LH
luteinizing hormone  stimulates
Leydig cells to make testosterone
Presence of testosterone inhibits
the further secretion of LH and
testosterone levels are thus
stabilized.
A negative feedback system.
Within the seminiferous tubules,
testosterone maintains
spermatogenesis

Anterior pituitary, releases follicle
stimulating hormone (FSH) -> promotes support of sperm cells

Produce a hormone known as inhibin -> inhibits secretion of FSH by the anterior pituitary (negative feedback loop)

1, Seminal vesicle;
2, ampulla of vas deferens;
3, bladder

urethral muscle surrounding pelvic
urethra;
• 5, bulbospongiosus muscle;
• 6, ischiocavernosus muscle

7, retractor penis muscle;
• 8, glans penis;
9, preputial membrane and cavity

1, Seminal vesicle;

2, ampulla of spermatic cord

3, bladder

7, refractor penis muscle;
• 8, glans penis;
9, preputial membrane and cavity

Maintenance of libido (sexual drive)
• Regulates secretory activity of the
accessory sex glands
• Secondary sexual characteristics
• Increased bone growth
• Greater muscling
• Thicker skin
• Deeper voice (in the bull)

Steroid sex hormone produced
by the ovary (granulosa cells of
follicles), placenta, and adrenal
cortex
• Female sex steroids from
developing follicle
• Promotes:
• female secondary sex
characteristics, estrus behavior
(sexual receptivity)

endometrial gland growth

duct growth in mammary gland

LH secretion

Steroid sex hormone produced by the
corpus luteum (CL) of the ovary, placenta,
and adrenal cortex.
• It is the principal progestational hormone –
required for pregnancy
• The functions of progesterone include:
1. Promotion of endometrial gland growth,
2. Stimulation of secretory activity of the
oviduct and endometrial glands to
provide nutrients for the developing
embryo before implantation,

3. Promotion of growth in mammary gland

4. 4. Prevention of contractility of the uterus during pregnany

5. Regulation

Maintenance of libido (sexual drive)
• Regulates secretory activity of the
accessory sex glands
• Secondary sexual characteristics
• Increased bone growth
• Greater muscling
• Thicker skin
• Deeper voice (in the bull)

Steroid sex hormone produced
by the ovary (granulosa cells of
follicles), placenta, and adrenal
cortex
• Female sex steroids from
developing follicle
• Promotes:
• female secondary sex
characteristics, estrus behavior
(sexual receptivity)

endometrial gland growth

duct growth in mammary gland

LH secretion

Steroid sex hormone produced by the
corpus luteum (CL) of the ovary, placenta,
and adrenal cortex.
• It is the principal progestational hormone –
required for pregnancy
• The functions of progesterone include:
1. Promotion of endometrial gland growth,
2. Stimulation of secretory activity of the
oviduct and endometrial glands to
provide nutrients for the developing
embryo before implantation,

3. Promotion of growth in mammary gland

4. 4. Prevention of contractility of the uterus during pregnany

5. Regulation

Maintenance of libido (sexual drive)
• Regulates secretory activity of the
accessory sex glands
• Secondary sexual characteristics
• Increased bone growth
• Greater muscling
• Thicker skin
• Deeper voice (in the bull)

Steroid sex hormone produced
by the ovary (granulosa cells of
follicles), placenta, and adrenal
cortex
• Female sex steroids from
developing follicle
• Promotes:
• female secondary sex
characteristics, estrus behavior
(sexual receptivity)

endometrial gland growth

duct growth in mammary gland

LH secretion

Steroid sex hormone produced by the
corpus luteum (CL) of the ovary, placenta,
and adrenal cortex.
• It is the principal progestational hormone –
required for pregnancy
• The functions of progesterone include:
1. Promotion of endometrial gland growth,
2. Stimulation of secretory activity of the
oviduct and endometrial glands to
provide nutrients for the developing
embryo before implantation,

3. Promotion of growth in mammary gland

4. 4. Prevention of contractility of the uterus during pregnany

5. Regulation

Maintenance of libido (sexual drive)
• Regulates secretory activity of the
accessory sex glands
• Secondary sexual characteristics
• Increased bone growth
• Greater muscling
• Thicker skin
• Deeper voice (in the bull)

Steroid sex hormone produced
by the ovary (granulosa cells of
follicles), placenta, and adrenal
cortex
• Female sex steroids from
developing follicle
• Promotes:
• female secondary sex
characteristics, estrus behavior
(sexual receptivity)

endometrial gland growth

duct growth in mammary gland

LH secretion

Steroid sex hormone produced by the
corpus luteum (CL) of the ovary, placenta,
and adrenal cortex.
• It is the principal progestational hormone –
required for pregnancy
• The functions of progesterone include:
1. Promotion of endometrial gland growth,
2. Stimulation of secretory activity of the
oviduct and endometrial glands to
provide nutrients for the developing
embryo before implantation,

3. Promotion of growth in mammary gland

4. 4. Prevention of contractility of the uterus during pregnany

5. Regulation

Follicle-stimulating hormone (FSH) and
luteinizing hormone (LH) from pars
distalis of anterior pituitary
• FSH  Promotes follicular growth 
ovulation
• LH  promotes ovulation  corpus
luteum (CL) formation
• Regulated by GnRH from
hypothalamus

Two ovaries
• Tubular genital tract
• Two uterine tubes
• Uterus
• Vagina
• External genitalia

Paired glands that
provide for the
development of oocytes
and for the production
of hormones.
• Caudal to its respective
right or left kidney
• Broad ligament  attaches ovaries to the dorsal wall of the abdomen

Provides a place for development of the
fetus if fertilization has occurred.
• Corpus (body),
• Cervix (neck),
• Two cornua (horns).
• The corpus is largest in the mare, less
extensive in the cow and sheep, and
small in the sow and bitch

Projects caudally into the
vagina
• Heavy, smooth muscle
sphincter is tightly closed,
except during estrus and at
parturition (birth of young).
• Secretes mucus at estrus
• Secretion of mucus during
pregnancy prevents

Two ovaries
• Tubular genital tract
• Two uterine tubes
• Uterus
• Vagina
• External genitalia

Paired glands that
provide for the
development of oocytes
and for the production
of hormones.
• Caudal to its respective
right or left kidney
• Broad ligament  attaches ovaries to the dorsal wall of the abdomen

Provides a place for development of the
fetus if fertilization has occurred.
• Corpus (body),
• Cervix (neck),
• Two cornua (horns).
• The corpus is largest in the mare, less
extensive in the cow and sheep, and
small in the sow and bitch

Projects caudally into the
vagina
• Heavy, smooth muscle
sphincter is tightly closed,
except during estrus and at
parturition (birth of young).
• Secretes mucus at estrus
• Secretion of mucus during
pregnancy prevents

Two ovaries
• Tubular genital tract
• Two uterine tubes
• Uterus
• Vagina
• External genitalia

Paired glands that
provide for the
development of oocytes
and for the production
of hormones.
• Caudal to its respective
right or left kidney
• Broad ligament  attaches ovaries to the dorsal wall of the abdomen

Provides a place for development of the
fetus if fertilization has occurred.
• Corpus (body),
• Cervix (neck),
• Two cornua (horns).
• The corpus is largest in the mare, less
extensive in the cow and sheep, and
small in the sow and bitch

FETAL DEVELOPMENT

Projects caudally into the
vagina
• Heavy, smooth muscle
sphincter is tightly closed,
except during estrus and at
parturition (birth of young).
• Secretes mucus at estrus
• Secretion of mucus during
pregnancy prevents

Two ovaries
• Tubular genital tract
• Two uterine tubes
• Uterus
• Vagina
• External genitalia

Paired glands that
provide for the
development of oocytes
and for the production
of hormones.
• Caudal to its respective
right or left kidney
• Broad ligament  attaches ovaries to the dorsal wall of the abdomen

Provides a place for development of the
fetus if fertilization has occurred.
• Corpus (body),
• Cervix (neck),
• Two cornua (horns).
• The corpus is largest in the mare, less
extensive in the cow and sheep, and
small in the sow and bitch

Projects caudally into the
vagina
• Heavy, smooth muscle
sphincter is tightly closed,
except during estrus and at
parturition (birth of young).
• Secretes mucus at estrus
• Secretion of mucus during
pregnancy prevents

Contain a single oocyte that
is surrounded by a single
layer of granulosa cells

MIDDLE

Visible antrum (open space)

Contain a single oocyte that
is surrounded by a single
layer of granulosa cells

MIDDLE

Visible antrum (open space)

Contain a single oocyte that
is surrounded by a single
layer of granulosa cells

MIDDLE

Visible antrum (open space)

Aka oviducts or fallopian tubes.
• They are paired, convoluted tubes that
conduct oocytes from the ovaries to the
respective horn of the uterus
Serve as the site for
fertilization of released oocytes by
spermatozoa in domestic species.
• The portion of each tube adjacent to its
respective ovary expands to form the
infundibulum
• Fimbria project from its free edge.
• The fimbria assist in directing the

Glandular
• Lined with simple columnar
epithelium
• Thickness varies with
hormonal activity

Smooth muscle
• Undergoes hypertrophy and
hyperplasia in pregnancy

Visceral peritoneum
• Outermost layer

Provides Protection

Aka oviducts or fallopian tubes.
• They are paired, convoluted tubes that
conduct oocytes from the ovaries to the
respective horn of the uterus
Serve as the site for
fertilization of released oocytes by
spermatozoa in domestic species.
• The portion of each tube adjacent to its
respective ovary expands to form the
infundibulum
• Fimbria project from its free edge.
• The fimbria assist in directing the

Glandular
• Lined with simple columnar
epithelium
• Thickness varies with
hormonal activity

Smooth muscle
• Undergoes hypertrophy and
hyperplasia in pregnancy

Visceral peritoneum
• Outermost layer

Provides Protection

Aka oviducts or fallopian tubes.
• They are paired, convoluted tubes that
conduct oocytes from the ovaries to the
respective horn of the uterus
Serve as the site for
fertilization of released oocytes by
spermatozoa in domestic species.
• The portion of each tube adjacent to its
respective ovary expands to form the
infundibulum
• Fimbria project from its free edge.
• The fimbria assist in directing the

Glandular
• Lined with simple columnar
epithelium
• Thickness varies with
hormonal activity

Smooth muscle
• Undergoes hypertrophy and
hyperplasia in pregnancy

Visceral peritoneum
• Outermost layer

Provides Protection

Aka oviducts or fallopian tubes.
• They are paired, convoluted tubes that
conduct oocytes from the ovaries to the
respective horn of the uterus
Serve as the site for
fertilization of released oocytes by
spermatozoa in domestic species.
• The portion of each tube adjacent to its
respective ovary expands to form the
infundibulum
• Fimbria project from its free edge.
• The fimbria assist in directing the

Glandular
• Lined with simple columnar
epithelium
• Thickness varies with
hormonal activity

Smooth muscle
• Undergoes hypertrophy and
hyperplasia in pregnancy

Visceral peritoneum
• Outermost layer

Provides Protection

Portion of the birth canal
located within the pelvis
• Between the uterus
cranially and the vulva
caudally
• The vagina serves as a
sheath for the male penis
during copulation

Caudal portion of the female
genitalia that extends from the vagina to
the exterior.
• The external urethral orifice (opening) is
the landmark junction of the vagina and
the vulva

Lips of the vulva
• The external part of the vulva is its
vertical opening

Female vestigial counterpart of the penis, concealed by the lowest part of the nerve endings

Portion of the birth canal
located within the pelvis
• Between the uterus
cranially and the vulva
caudally
• The vagina serves as a
sheath for the male penis
during copulation

Caudal portion of the female
genitalia that extends from the vagina to
the exterior.
• The external urethral orifice (opening) is
the landmark junction of the vagina and
the vulva

Lips of the vulva
• The external part of the vulva is its
vertical opening

Female vestigial counterpart of the penis, concealed by the lowest part of the nerve endings

Portion of the birth canal
located within the pelvis
• Between the uterus
cranially and the vulva
caudally
• The vagina serves as a
sheath for the male penis
during copulation

Caudal portion of the female
genitalia that extends from the vagina to
the exterior.
• The external urethral orifice (opening) is
the landmark junction of the vagina and
the vulva

Lips of the vulva
• The external part of the vulva is its
vertical opening

Female vestigial counterpart of the penis, concealed by the lowest part of the nerve endings

Portion of the birth canal
located within the pelvis
• Between the uterus
cranially and the vulva
caudally
• The vagina serves as a
sheath for the male penis
during copulation

Caudal portion of the female
genitalia that extends from the vagina to
the exterior.
• The external urethral orifice (opening) is
the landmark junction of the vagina and
the vulva

Lips of the vulva
• The external part of the vulva is its
vertical opening

Female vestigial counterpart of the penis, concealed by the lowest part of the nerve endings

The time of sexual receptivity,
sometimes referred to as heat.
Ovulation usually, but not always,
occurs at the end of estrus.

The early postovulatory
period, during which the CL begins
development

The period of mature luteal
activity, which begins about 4 days
after ovulation and ends with
regression of the CL

he period beginning after
CL regression and ending at the onset
of estrus. During proestrus, rapid follicle development leads to ovulation and to the onset of sexual receptivity

The follicular periods (proestrus and estrus) are characterized by estrogen dominance

Diestrus/sexually nonreceptive period includes metestrus, diestrus, and proestrus

The time of sexual receptivity,
sometimes referred to as heat.
Ovulation usually, but not always,
occurs at the end of estrus.

The early postovulatory
period, during which the CL begins
development

The period of mature luteal
activity, which begins about 4 days
after ovulation and ends with
regression of the CL

he period beginning after
CL regression and ending at the onset
of estrus. During proestrus, rapid follicle development leads to ovulation and to the onset of sexual receptivity

The follicular periods (proestrus and estrus) are characterized by estrogen dominance

Diestrus/sexually nonreceptive period includes metestrus, diestrus, and proestrus

The time of sexual receptivity,
sometimes referred to as heat.
Ovulation usually, but not always,
occurs at the end of estrus.

The early postovulatory
period, during which the CL begins
development

The period of mature luteal
activity, which begins about 4 days
after ovulation and ends with
regression of the CL

he period beginning after
CL regression and ending at the onset
of estrus. During proestrus, rapid follicle development leads to ovulation and to the onset of sexual receptivity

The follicular periods (proestrus and estrus) are characterized by estrogen dominance

Diestrus/sexually nonreceptive period includes metestrus, diestrus, and proestrus

The time of sexual receptivity,
sometimes referred to as heat.
Ovulation usually, but not always,
occurs at the end of estrus.

The early postovulatory
period, during which the CL begins
development

The period of mature luteal
activity, which begins about 4 days
after ovulation and ends with
regression of the CL

The period beginning after
CL regression and ending at the onset
of estrus. During proestrus, rapid follicle development leads to ovulation and to the onset of sexual receptivity

The follicular periods (proestrus and estrus) are characterized by estrogen dominance

Diestrus/sexually nonreceptive period includes metestrus, diestrus, and proestrus

queen, doe, ewe, and mare.
• These animals are sexually inactive during certain times
of the year.
• Associated with relative lengths of alternating periods of
lightness and darkness.

• Become anestrous (without estrous cycles) late in
the fall (“turn-off time”) because of decreasing light,
• Ovarian cycles are resumed in late winter or early
spring (“turn-on time”) by increasing light.
• Long day breeders

Ovarian cycle has a turn-on time associated with a decrease in daylight and a turn off time associated with a increase in daylight

short day breeders

queen, doe, ewe, and mare.
• These animals are sexually inactive during certain times
of the year.
• Associated with relative lengths of alternating periods of
lightness and darkness.

• Become anestrous (without estrous cycles) late in
the fall (“turn-off time”) because of decreasing light,
• Ovarian cycles are resumed in late winter or early
spring (“turn-on time”) by increasing light.
• Long day breeders

Ovarian cycle has a turn-on time associated with a decrease in daylight and a turn off time associated with a increase in daylight

short day breeders

queen, doe, ewe, and mare.
• These animals are sexually inactive during certain times
of the year.
• Associated with relative lengths of alternating periods of
lightness and darkness.

• Become anestrous (without estrous cycles) late in
the fall (“turn-off time”) because of decreasing light,
• Ovarian cycles are resumed in late winter or early
spring (“turn-on time”) by increasing light.
• Long day breeders

Ovarian cycle has a turn-on time associated with a decrease in daylight and a turn off time associated with a increase in daylight

short day breeders

Hormones similar but endometrial
lining shed at end of diestrus

Can be bred at any phase of heat
cycle
• Cervical stimulation (barbed cat penis)
triggers neuroendocrine reflex

No cycle always ready to mate unless pregnant

Hormones similar but endometrial
lining shed at end of diestrus

Can be bred at any phase of heat
cycle
• Cervical stimulation (barbed cat penis)
triggers neuroendocrine reflex

No cycle always ready to mate unless pregnant

Hormones similar but endometrial
lining shed at end of diestrus

Can be bred at any phase of heat
cycle
• Cervical stimulation (barbed cat penis)
triggers neuroendocrine reflex

No cycle always ready to mate unless pregnant

With pregnancy or without pregnancy
 Leads to luteolysis (lessening of the C
 Recognition of pregnancy

Pregnant mare serum
gonadotropin/equine chorionic
gonadotropin
• From endometrial cups of pregnant ma
uterus
• Used by humans to induce ovulation in
horses

With pregnancy or without pregnancy
 Leads to luteolysis (lessening of the C
 Recognition of pregnancy

Pregnant mare serum
gonadotropin/equine chorionic
gonadotropin
• From endometrial cups of pregnant ma
uterus
• Used by humans to induce ovulation in
horses

Chorion - outermost, attaches
to uterus

Allantois – below chorion
Amnion – encloses embryo

Chorion - outermost, attaches
to uterus

Allantois – encloses embryo
Amnion – below chorion

Allantoic - holds waste products

Amnion - holds amniotic fluid, viscus, provides protection and cushion

Allantoic - holds amniotic fluid, viscus, provides protection and cushion

Amnion - holds waste products

Chorion - outermost, attaches
to uterus

Allantois – below chorion
Amnion – encloses embryo

Chorion - outermost, attaches
to uterus

Allantois – encloses embryo
Amnion – below chorion

Allantoic - holds waste products

Amnion - holds amniotic fluid, viscus, provides protection and cushion

Allantoic - holds amniotic fluid, viscus, provides protection and cushion

Amnion - holds waste products

When the attachment (extension of
chorionic villi) of fetal membranes to the endometrium is
continuous throughout the entire surface of the fetal
membranes
• Found in the horse and pig

Attachment occurs only at the
many mushroom-like projections from the endometrium
• The fetal cotyledons are attached to the maternal caruncles,
a combination known as a placentome
• In ruminants

Attached by a girdle-like band that encircles the placenta

in dogs and cats

Attachment is confined to a disk-shaped area

human and rat

When the attachment (extension of
chorionic villi) of fetal membranes to the endometrium is
continuous throughout the entire surface of the fetal
membranes
• Found in the horse and pig

Attachment occurs only at the
many mushroom-like projections from the endometrium
• The fetal cotyledons are attached to the maternal caruncles,
a combination known as a placentome
• In ruminants

Attached by a girdle-like band that encircles the placenta

in dogs and cats

Attachment is confined to a disk-shaped area

human and rat

When the attachment (extension of
chorionic villi) of fetal membranes to the endometrium is
continuous throughout the entire surface of the fetal
membranes
• Found in the horse and pig

Attachment occurs only at the
many mushroom-like projections from the endometrium
• The fetal cotyledons are attached to the maternal caruncles,
a combination known as a placentome
• In ruminants

Attached by a girdle-like band that encircles the placenta

in dogs and cats

Attachment is confined to a disk-shaped area

human and rat

When the attachment (extension of
chorionic villi) of fetal membranes to the endometrium is
continuous throughout the entire surface of the fetal
membranes
• Found in the horse and pig

Attachment occurs only at the
many mushroom-like projections from the endometrium
• The fetal cotyledons are attached to the maternal caruncles,
a combination known as a placentome
• In ruminants

Attached by a girdle-like band that encircles the placenta

in dogs and cats

Attachment is confined to a disk-shaped area

human and rat

Rid body of nitrogenous waste
• Protein breakdown
Water and acid/base balance

Toxin/drug elimination
Breakdown product elimination
Produces hormones (erythropoietin, renin)

Proteins -> amino acids -> COOH + -NH2 -> Ammonia + Urea + Uric Acid

Proteins -> amino acids -> -NH2+ COOH -> Ammonia + Urea + Uric Acid

Fish, aquatic
invertebrates
• Aquatic animals  water can reduce
toxicity of ammonia
• Very toxic
• Water soluble
• Fish produce ammonia  tanks 
nitrifying bacteria introduced from
nitrogen cycle

Birds, reptiles,
have the renal portal system
• Formed in the liver, concentrates,
becomes precipitant
• Semi-solid.
• Acidic
• Requires very little water
• Requires a lot of energy

Mammals,
amphibians, sharks
• Allows water balance
• More/less excreted depending
on conditions
• Relatively low toxicity
• Build up of urea can cause
problems, including neurologic
problems

Fish, aquatic
invertebrates
• Aquatic animals  water can reduce
toxicity of ammonia
• Very toxic
• Water soluble
• Fish produce ammonia  tanks 
nitrifying bacteria introduced from
nitrogen cycle

Birds, reptiles,
have the renal portal system
• Formed in the liver, concentrates,
becomes precipitant
• Semi-solid.
• Acidic
• Requires very little water
• Requires a lot of energy

Mammals,
amphibians, sharks
• Allows water balance
• More/less excreted depending
on conditions
• Relatively low toxicity
• Build up of urea can cause
problems, including neurologic
problems

Fish, aquatic
invertebrates
• Aquatic animals  water can reduce
toxicity of ammonia
• Very toxic
• Water soluble
• Fish produce ammonia  tanks 
nitrifying bacteria introduced from
nitrogen cycle

Birds, reptiles,
have the renal portal system
• Formed in the liver, concentrates,
becomes precipitant
• Semi-solid.
• Acidic
• Requires very little water
• Requires a lot of energy

Mammals,
amphibians, sharks
• Allows water balance
• More/less excreted depending
on conditions
• Relatively low toxicity
• Build up of urea can cause
problems, including neurologic
problems

Separated in
the abdominal cavity; they
have their own peritoneum

Indentation where renal
artery enters, renal vein and
ureter leave

Most species

Cattle, dolphins. birds but long

Separated in
the abdominal cavity; they
have their own peritoneum

Indentation where renal
artery enters, renal vein and
ureter leave

Most species

Cattle, dolphins. birds but long

Separated in
the abdominal cavity; they
have their own peritoneum

Indentation where renal
artery enters, renal vein and
ureter leave

Most species

Cattle, dolphins. birds but long

Functional unit off the kidney

Glomerulus
• Bowman’s capsule
• Proximal Convoluted Tubule
(PCT)
• Loop of Henle
• Distal Convoluted Tubule (DCT)

Capillary tuft
o Afferent arteriole: brings blood in
o Efferent arteriole: drains blood out
o This is the filter

Podocytes = visceral layer
o Parietal layer = simple squamous epithelium
o Both podocytes and simple squam
epithelium necessary for filtration
o Sits above capillaries
o Receives filtrate

Functional unit off the kidney

Glomerulus
• Bowman’s capsule
• Proximal Convoluted Tubule
(PCT)
• Loop of Henle
• Distal Convoluted Tubule (DCT)

Capillary tuft
o Afferent arteriole: brings blood in
o Efferent arteriole: drains blood out
o This is the filter

Podocytes = visceral layer
o Parietal layer = simple squamous epithelium
o Both podocytes and simple squam
epithelium necessary for filtration
o Sits above capillaries
o Receives filtrate

Functional unit off the kidney

Glomerulus
• Bowman’s capsule
• Proximal Convoluted Tubule
(PCT)
• Loop of Henle
• Distal Convoluted Tubule (DCT)

Capillary tuft
o Afferent arteriole: brings blood in
o Efferent arteriole: drains blood out
o This is the filter

Podocytes = visceral layer
o Parietal layer = simple squamous epithelium
o Both podocytes and simple squam
epithelium necessary for filtration
o Sits above capillaries
o Receives filtrate

Simple cuboidal epithelium 
increases surface area

Mostly simple squamous epithelium
• Goes down into medulla

Thin: simple squamous epithelium
(#4)
• Thick: simple cuboidal epithelium for
strength (#5)
• Goes up to cortex

Simple cuboidal epithelium 
increases surface area

Mostly simple squamous epithelium
• Goes down into medulla

Thin: simple squamous epithelium
(#4)
• Thick: simple cuboidal epithelium for
strength (#5)
• Goes up to cortex

Simple cuboidal epithelium 
increases surface area

Mostly simple squamous epithelium
• Goes down into medulla

Thin: simple squamous epithelium
(#4)
• Thick: simple cuboidal epithelium for
strength (#5)
• Goes up to cortex

Simple cuboidal epithelium  increases
surface area
• Convoluted

Simple cuboidal epithelium with NO brush
border

Capillary network in the medulla  around
loop of Henle  essential for flow of filtrate

Simple cuboidal epithelium  increases
surface area
• Convoluted

Simple cuboidal epithelium with NO brush
border

Capillary network in the medulla  around
loop of Henle  essential for flow of filtrate

Simple cuboidal epithelium  increases
surface area
• Convoluted

Simple cuboidal epithelium with NO brush
border

Capillary network in the medulla  around
loop of Henle  essential for flow of filtrate

Tubes from renal pelvis (leave hilus)
of the kidney to neck of urinary
bladder
• Angle prevents backflow
Smooth muscle and loose
connective tissue in walls
• Lined with TRANSITIONAL (urinary)
epithelium

Area at neck of bladder
where ureters enter and urethra
leaves

1. Serosal epithelium
2. Large layer of smooth muscle (detrusor muscle)
3. Transitional epithelium (lines lumen)
• Cells slide apart and flatten to fewer layers as organ fills with urine

Tubes from renal pelvis (leave hilus)
of the kidney to neck of urinary
bladder
• Angle prevents backflow
Smooth muscle and loose
connective tissue in walls
• Lined with TRANSITIONAL (urinary)
epithelium

Area at neck of bladder
where ureters enter and urethra
leaves

1. Serosal epithelium
2. Large layer of smooth muscle (detrusor muscle)
3. Transitional epithelium (lines lumen)
• Cells slide apart and flatten to fewer layers as organ fills with urine

Tubes from renal pelvis (leave hilus)
of the kidney to neck of urinary
bladder
• Angle prevents backflow
Smooth muscle and loose
connective tissue in walls
• Lined with TRANSITIONAL (urinary)
epithelium

Area at neck of bladder
where ureters enter and urethra
leaves

1. Serosal epithelium
2. Large layer of smooth muscle (detrusor muscle)
3. Transitional epithelium (lines lumen)
• Cells slide apart and flatten to fewer layers as organ fills with urine

Urine is conveyed to the urinary bladder
from the renal pelvis by peristalsis and
enters at the ureterovesicular junction

During micturition (emptying of the
urinary bladder), urine is directed
through the neck of the bladder to the
urethra

Urine does not reenter the ureter
because the ureterovesicular junction is
closed by the hydrostatic pressure of
urine

Urine does reenter the ureter
because the ureterovesicular junction is
closed by the hydrostatic pressure of
urine

Caudal continuation of the bladder
• Tube from neck of urinary bladder to
outside
• Longer in males; goes through penis
• Less prone to lower urinary tract
infections (UTI)
• Starts as transitional (urinary) epithelium
lining lumen  changes to moist stratified
squamous epithelium (adds protection)
• Urine is sterile until it exits the body

From glomerular filtrate into 
cells of tubules of nephron  to
blood

From blood  into cells of
tubules of nephron  to fluid in
tubules

Most of water
• Fine tune water
• Acid/base balance

Caudal continuation of the bladder
• Tube from neck of urinary bladder to
outside
• Longer in males; goes through penis
• Less prone to lower urinary tract
infections (UTI)
• Starts as transitional (urinary) epithelium
lining lumen  changes to moist stratified
squamous epithelium (adds protection)
• Urine is sterile until it exits the body

From glomerular filtrate into 
cells of tubules of nephron  to
blood

From blood  into cells of
tubules of nephron  to fluid in
tubules

Most of water
• Fine tune water
• Acid/base balance

Caudal continuation of the bladder
• Tube from neck of urinary bladder to
outside
• Longer in males; goes through penis
• Less prone to lower urinary tract
infections (UTI)
• Starts as transitional (urinary) epithelium
lining lumen  changes to moist stratified
squamous epithelium (adds protection)
• Urine is sterile until it exits the body

From glomerular filtrate into 
cells of tubules of nephron  to
blood

From blood  into cells of
tubules of nephron  to fluid in
tubules

Most of water
• Fine tune water
• Acid/base balance

Caudal continuation of the bladder
• Tube from neck of urinary bladder to
outside
• Longer in males; goes through penis
• Less prone to lower urinary tract
infections (UTI)
• Starts as transitional (urinary) epithelium
lining lumen  changes to moist stratified
squamous epithelium (adds protection)
• Urine is sterile until it exits the body

From glomerular filtrate into 
cells of tubules of nephron  to
blood

From blood  into cells of
tubules of nephron  to fluid in
tubules

Most of water
• Fine tune water
• Acid/base balance

fenestrated capillaries = spaces
between glomerular endothelial cells

Substances from leaky capillaries goes to

Product of filtration (not urine yet)
- Water, NaCL, K+, Ca++, Cl-, Mg+,
bicarbonate, urea, glucose, AA’s, lipids, small proteins

fenestrated capillaries = spaces
between glomerular endothelial cells

Substances from leaky capillaries goes to

Product of filtration (not urine yet)
- Water, NaCL, K+, Ca++, Cl-, Mg+,
bicarbonate, urea, glucose, AA’s, lipids, small proteins

fenestrated capillaries = spaces
between glomerular endothelial cells

Substances from leaky capillaries goes to

Product of filtration (not urine yet)
- Water, NaCL, K+, Ca++, Cl-, Mg+,
bicarbonate, urea, glucose, AA’s, lipids, small proteins

(glomerular filtration)
• Glucose reabsorption by active
transport
• 65% of water that entered gets sent
back to the blood via osmosis
• Amino acids coupled with sodium
cotransport, needs energy
• Peritubular capillary reabsorption:
NaCl and K+
• Water will follow NaCl back into the
blood
 90% of bicarbonate is reabsorbed
back into the blood.

After PCT, filtrate goes from cortex to
medulla (LOH)
• Medulla has higher osmolarity than
cortex and filtrate

Water permeable, solute
impermeable
• Water follows by osmosis via
channel (aquaporin)

Sodium and chloride resorbed
by active transport
 Not followed by water
 Bottom of loop  most
concentrated area

Sodium resorbed by active transport
 Influenced by aldosterone
• Water resorbed by osmosis
 Influenced by antidiuretic hormone (ADH,
produced by posterior pituitary)
• Hydrogen ions and some drugs secreted by active
transport – acid/base balance
Secretion: anything in the blood sent out to urine
(toxins, bicarb or H+, drugs, meds)

(glomerular filtration)
• Glucose reabsorption by active
transport
• 65% of water that entered gets sent
back to the blood via osmosis
• Amino acids coupled with sodium
cotransport, needs energy
• Peritubular capillary reabsorption:
NaCl and K+
• Water will follow NaCl back into the
blood
 90% of bicarbonate is reabsorbed
back into the blood.

After PCT, filtrate goes from cortex to
medulla (LOH)
• Medulla has higher osmolarity than
cortex and filtrate

Water permeable, solute
impermeable
• Water follows by osmosis via
channel (aquaporin)

Sodium and chloride resorbed
by active transport
 Not followed by water
 Bottom of loop  most
concentrated area

Sodium resorbed by active transport
 Influenced by aldosterone
• Water resorbed by osmosis
 Influenced by antidiuretic hormone (ADH,
produced by posterior pituitary)
• Hydrogen ions and some drugs secreted by active
transport – acid/base balance
Secretion: anything in the blood sent out to urine
(toxins, bicarb or H+, drugs, meds)

(glomerular filtration)
• Glucose reabsorption by active
transport
• 65% of water that entered gets sent
back to the blood via osmosis
• Amino acids coupled with sodium
cotransport, needs energy
• Peritubular capillary reabsorption:
NaCl and K+
• Water will follow NaCl back into the
blood
 90% of bicarbonate is reabsorbed
back into the blood.

After PCT, filtrate goes from cortex to
medulla (LOH)
• Medulla has higher osmolarity than
cortex and filtrate

Water permeable, solute
impermeable
• Water follows by osmosis via
channel (aquaporin)

Sodium and chloride resorbed
by active transport
 Not followed by water
 Bottom of loop  most
concentrated area

Sodium resorbed by active transport
 Influenced by aldosterone
• Water resorbed by osmosis
 Influenced by antidiuretic hormone (ADH,
produced by posterior pituitary)
• Hydrogen ions and some drugs secreted by active
transport – acid/base balance
Secretion: anything in the blood sent out to urine
(toxins, bicarb or H+, drugs, meds)

(glomerular filtration)
• Glucose reabsorption by active
transport
• 65% of water that entered gets sent
back to the blood via osmosis
• Amino acids coupled with sodium
cotransport, needs energy
• Peritubular capillary reabsorption:
NaCl and K+
• Water will follow NaCl back into the
blood
 90% of bicarbonate is reabsorbed
back into the blood.

After PCT, filtrate goes from cortex to
medulla (LOH)
• Medulla has higher osmolarity than
cortex and filtrate

Water permeable, solute
impermeable
• Water follows by osmosis via
channel (aquaporin)

Sodium and chloride resorbed
by active transport
 Not followed by water
 Bottom of loop  most
concentrated area

Sodium resorbed by active transport
 Influenced by aldosterone
• Water resorbed by osmosis
 Influenced by antidiuretic hormone (ADH,
produced by posterior pituitary)
• Hydrogen ions and some drugs secreted by active
transport – acid/base balance
Secretion: anything in the blood sent out to urine
(toxins, bicarb or H+, drugs, meds)

(glomerular filtration)
• Glucose reabsorption by active
transport
• 65% of water that entered gets sent
back to the blood via osmosis
• Amino acids coupled with sodium
cotransport, needs energy
• Peritubular capillary reabsorption:
NaCl and K+
• Water will follow NaCl back into the
blood
 90% of bicarbonate is reabsorbed
back into the blood.

After PCT, filtrate goes from cortex to
medulla (LOH)
• Medulla has higher osmolarity than
cortex and filtrate

Water permeable, solute
impermeable
• Water follows by osmosis via
channel (aquaporin)

Sodium and chloride resorbed
by active transport
 Not followed by water
 Bottom of loop  most
concentrated area

Sodium resorbed by active transport
 Influenced by aldosterone
• Water resorbed by osmosis
 Influenced by antidiuretic hormone (ADH,
produced by posterior pituitary)
• Hydrogen ions and some drugs secreted by active
transport – acid/base balance
Secretion: anything in the blood sent out to urine
(toxins, bicarb or H+, drugs, meds)

Creates concentration
gradient to pass materials from one
tubule to another

Hypertonic  Sodium and urea
in interstitial fluid
• Driving force of water going out is high,
solute concentration on outside is high

Isotonic to hypotonic

Tubular fluid into loop of Henle is
hypotonic
• Becomes hypertonic at bottom of loop
Loses water on the way down and
becomes concentrated
• Becomes hypotonic during ascent
Loses sodium/solutes and becomes
dilute
• Becomes hypertonic in collecting duct
Loses wate

Creates concentration
gradient to pass materials from one
tubule to another

Hypertonic  Sodium and urea
in interstitial fluid
• Driving force of water going out is high,
solute concentration on outside is high

Isotonic to hypotonic

Tubular fluid into loop of Henle is
hypotonic
• Becomes hypertonic at bottom of loop
Loses water on the way down and
becomes concentrated
• Becomes hypotonic during ascent
Loses sodium/solutes and becomes
dilute
• Becomes hypertonic in collecting duct
Loses wate

Creates concentration
gradient to pass materials from one
tubule to another

Hypertonic  Sodium and urea
in interstitial fluid
• Driving force of water going out is high,
solute concentration on outside is high

Isotonic to hypotonic

Tubular fluid into loop of Henle is
hypotonic
• Becomes hypertonic at bottom of loop
Loses water on the way down and
becomes concentrated
• Becomes hypotonic during ascent
Loses sodium/solutes and becomes
dilute
• Becomes hypertonic in collecting duct
Loses wate

Creates concentration
gradient to pass materials from one
tubule to another

Hypertonic  Sodium and urea
in interstitial fluid
• Driving force of water going out is high,
solute concentration on outside is high

Isotonic to hypotonic

Tubular fluid into loop of Henle is
hypotonic
• Becomes hypertonic at bottom of loop
Loses water on the way down and
becomes concentrated
• Becomes hypotonic during ascent
Loses sodium/solutes and becomes
dilute
• Becomes hypertonic in collecting duct
Loses wate

Increased blood pressure yields increased
glomerular filtration rate (GFR) forcing
more blood into the glomerulus  urine forms
faster
• Lower blood pressure slows urine formation
• Specifically changing afferent or efferent
arteriole diameter

more blood flows
 increases GFR

lso increase
GFR

Increased blood pressure yields increased
glomerular filtration rate (GFR) forcing
more blood into the glomerulus  urine forms
faster
• Lower blood pressure slows urine formation
• Specifically changing afferent or efferent
arteriole diameter

more blood flows
 increases GFR

lso increase
GFR

Increased blood pressure yields increased
glomerular filtration rate (GFR) forcing
more blood into the glomerulus  urine forms
faster
• Lower blood pressure slows urine formation
• Specifically changing afferent or efferent
arteriole diameter

more blood flows
 increases GFR

lso increase
GFR

Juxtaglomerular apparatus (JG) =JG cells
and macula densa cells of DCT
Macula densa cells = chemoreceptors
around DCT
• Sense increased NaCl (high osmolarity)
in tubular fluid  slows GFR to increase
sodium resorption

Cycle of events for the relief of
hyperosmolality.
• Increased thirst is the predominant
factor for the correction of
hyperosmolality.
• Regulated by ADH, antidiuretic hormone
• Diabetes insipidus  disease where
no ADH is produced
 Can’t send water to body  animal
will keep drinking (polydipsia) 
increased urination (polyuria)

Causes sodium to be secreted
into urine at the CD  water
follows
• Increases urine volume
• Decreases urine concentration

Vasoconstriction of afferent arteriole  decreased GFR

Juxtaglomerular apparatus (JG) =JG cells
and macula densa cells of DCT
Macula densa cells = chemoreceptors
around DCT
• Sense increased NaCl (high osmolarity)
in tubular fluid  slows GFR to increase
sodium resorption

Cycle of events for the relief of
hyperosmolality.
• Increased thirst is the predominant
factor for the correction of
hyperosmolality.
• Regulated by ADH, antidiuretic hormone
• Diabetes insipidus  disease where
no ADH is produced
 Can’t send water to body  animal
will keep drinking (polydipsia) 
increased urination (polyuria)

Causes sodium to be secreted
into urine at the CD  water
follows
• Increases urine volume
• Decreases urine concentration

Vasoconstriction of afferent arteriole  decreased GFR

Juxtaglomerular apparatus (JG) =JG cells
and macula densa cells of DCT
Macula densa cells = chemoreceptors
around DCT
• Sense increased NaCl (high osmolarity)
in tubular fluid  slows GFR to increase
sodium resorption

Cycle of events for the relief of
hyperosmolality.
• Increased thirst is the predominant
factor for the correction of
hyperosmolality.
• Regulated by ADH, antidiuretic hormone
• Diabetes insipidus  disease where
no ADH is produced
 Can’t send water to body  animal
will keep drinking (polydipsia) 
increased urination (polyuria)

Causes sodium to be secreted
into urine at the CD  water
follows
• Increases urine volume
• Decreases urine concentration

Vasoconstriction of afferent arteriole  decreased GFR

Juxtaglomerular apparatus (JG) =JG cells
and macula densa cells of DCT
Macula densa cells = chemoreceptors
around DCT
• Sense increased NaCl (high osmolarity)
in tubular fluid  slows GFR to increase
sodium resorption

Cycle of events for the relief of
hyperosmolality.
• Increased thirst is the predominant
factor for the correction of
hyperosmolality.
• Regulated by ADH, antidiuretic hormone
• Diabetes insipidus  disease where
no ADH is produced
 Can’t send water to body  animal
will keep drinking (polydipsia) 
increased urination (polyuria)

Causes sodium to be secreted
into urine at the CD  water
follows
• Increases urine volume
• Decreases urine concentration

Vasoconstriction of afferent arteriole  decreased GFR

Break down and absorb food
– Takes in  digests food and water  breakdown 
reabsorb  eliminate solid waste product
– Increase surface area by mechanical breakdown
• Chewing and mixing
– Convert to simple molecules via enzymes
• Large surface area of digestive tract with folds, projections

One long muscular tube from mouth to anus
• Lumen is outside the body

Digestion: mechanical and chemical breakdown of food
Resorption: absorption from intestinal epithelium to blood
stream

Digestion: absorption from intestinal epithelium to blood
stream

Resorption: mechanical and chemical breakdown of food

Break down and absorb food
– Takes in  digests food and water  breakdown 
reabsorb  eliminate solid waste product
– Increase surface area by mechanical breakdown
• Chewing and mixing
– Convert to simple molecules via enzymes
• Large surface area of digestive tract with folds, projections

One long muscular tube from mouth to anus
• Lumen is outside the body

Digestion: mechanical and chemical breakdown of food
Resorption: absorption from intestinal epithelium to blood
stream

Digestion: absorption from intestinal epithelium to blood
stream

Resorption: mechanical and chemical breakdown of food

Single chamber stomach, simple non-ruminant

Humans pigs, mink, chickens, pigeons, ostrich

Ruminant - Sheep, cow, deer

Non-ruminant - Hippo

Cecal Fermenters - Rabbit

Caeco-colic Fermenters - Horses and elephants

Single chamber stomach, simple non-ruminant

Humans pigs, mink, chickens, pigeons, ostrich

Ruminant - Sheep, cow, deer

Non-ruminant - Hippo

Cecal Fermenters - Rabbit

Caeco-colic Fermenters - Horses and elephants

Single chamber stomach, simple non-ruminant

Humans pigs, mink, chickens, pigeons, ostrich

Ruminant - Sheep, cow, deer

Non-ruminant - Hippo

Cecal Fermenters - Rabbit

Caeco-colic Fermenters - Horses and elephants

Liver

Gall Bladder

Pancreas

Oral Cavity

Pharynx

Esophagus

Stomach

Small Intestine

Large Intestine

Liver

Gall Bladder

Pancreas

Oral Cavity

Pharynx

Esophagus

Stomach

Small Intestine

Large Intestine

Acquisition of food
– How an animal gets food into the oral
cavity
– Lips (equine), tongue (bovine), teeth,
hands (monkey), split lip and tongue
(ruminants

Chewing
– First mechanical breakdown
– Jaws, cheeks, tongue

Some chemical
digestion of starch to simple sugars
• Many herbivores and omnivores

Acquisition of food
– How an animal gets food into the oral
cavity
– Lips (equine), tongue (bovine), teeth,
hands (monkey), split lip and tongue
(ruminants

Chewing
– First mechanical breakdown
– Jaws, cheeks, tongue

Some chemical
digestion of starch to simple sugars
• Many herbivores and omnivores

Acquisition of food
– How an animal gets food into the oral
cavity
– Lips (equine), tongue (bovine), teeth,
hands (monkey), split lip and tongue
(ruminants

Chewing
– First mechanical breakdown
– Jaws, cheeks, tongue

Some chemical
digestion of starch to simple sugars
• Many herbivores and omnivores

Incisors - Biting off, cutting, front teeth

Canines - (Fang) tearing, sharp, 2 pairs, long, paired

Premolars - (Cheek Teeth), grinding

Molars - Grinding

Incisors - (Fang) tearing, sharp, 2 pairs, long, paired

Canines - Biting off, cutting, front teeth

Premolars - Grinding

Molars - (Cheek Teeth), grinding

Ruminants: No maxillary incisors  rough dental pad on
top jaw

Horses: Sharp incisors to grab forage once lips prehend
it

Horses: No maxillary incisors  rough dental pad on
top jaw

Ruminants: Sharp incisors to grab forage once lips prehend
it

Incisors - Biting off, cutting, front teeth

Canines - (Fang) tearing, sharp, 2 pairs, long, paired

Premolars - (Cheek Teeth), grinding

Molars - Grinding

Incisors - (Fang) tearing, sharp, 2 pairs, long, paired

Canines - Biting off, cutting, front teeth

Premolars - Grinding

Molars - (Cheek Teeth), grinding

Ruminants: No maxillary incisors  rough dental pad on
top jaw

Horses: Sharp incisors to grab forage once lips prehend
it

Horses: No maxillary incisors  rough dental pad on
top jaw

Ruminants: Sharp incisors to grab forage once lips prehend
it

Enamel: (white): outermost, white, very hard,
calcium and phosphorus

Cementum: (brown): middle, brown, acts as the
glue, connective tissue, binds tooth root to gum

Dentin: (yellowish): calcified tissue; odontoblasts

Enamel: (yellowish): calcified tissue; odontoblasts

Cementum: (white): outermost, white, very hard,
calcium and phosphorus

Dentin: (brown): middle, brown, acts as the
glue, connective tissue, binds tooth root to gum

Pulp Cavity: Blood and nerve supply

Crown: Above gumline

Root: Below gumline

Socket: unique joint called gomphosis

Pulp Cavity: Unique join called gomphosis

Crown: Below gumline

Root: Above gumline

Socket: Blood and nerve supply

Enamel: (white): outermost, white, very hard,
calcium and phosphorus

Cementum: (brown): middle, brown, acts as the
glue, connective tissue, binds tooth root to gum

Dentin: (yellowish): calcified tissue; odontoblasts

Enamel: (yellowish): calcified tissue; odontoblasts

Cementum: (white): outermost, white, very hard,
calcium and phosphorus

Dentin: (brown): middle, brown, acts as the
glue, connective tissue, binds tooth root to gum

Pulp Cavity: Blood and nerve supply

Crown: Above gumline

Root: Below gumline

Socket: unique joint called gomphosis

Pulp Cavity: Unique join called gomphosis

Crown: Below gumline

Root: Above gumline

Socket: Blood and nerve supply

Low crown,
• All carnivores
• Stop growing after eruption
• Pulp cavity in middle, surrounded by dentine,
cementum around root, enamel on surface
of crown

High crown
• Example, equine
• Continues to grow
• Pulp cavity does not extend above gumline
• Layers of enamel, cementum and dentine

Eruption of permanents most reliable
– Horses: pattern of wear of enamel,
cementum and dentine
– Horses and other large animals: shape
and length of teeth

Low crown,
• All carnivores
• Stop growing after eruption
• Pulp cavity in middle, surrounded by dentine,
cementum around root, enamel on surface
of crown

High crown
• Example, equine
• Continues to grow
• Pulp cavity does not extend above gumline
• Layers of enamel, cementum and dentine

Eruption of permanents most reliable
– Horses: pattern of wear of enamel,
cementum and dentine
– Horses and other large animals: shape
and length of teeth

Low crown,
• All carnivores
• Stop growing after eruption
• Pulp cavity in middle, surrounded by dentine,
cementum around root, enamel on surface
of crown

High crown
• Example, equine
• Continues to grow
• Pulp cavity does not extend above gumline
• Layers of enamel, cementum and dentine

Eruption of permanents most reliable
– Horses: pattern of wear of enamel,
cementum and dentine
– Horses and other large animals: shape
and length of teeth

Most of thickness is skeletal muscle in bundles 
moves in 3 different directions
• Keratinized stratified squamous epithelium,
papillae on dorsal surface (extra protection)

Fungiform: Taste Buds

Filiform: spikes, rough, traction for food, important for grooming (Rough cat tongue)

Moist stratified (non keratinized) squamous
epithelium, no papillae on ventral surface

Fungiform: spikes, rough, traction for food, important for grooming (Rough cat tongue)

Filiform: Taste buds

Moist stratified (non keratinized) squamous
epithelium, no papillae on ventral surface

Most of thickness is skeletal muscle in bundles 
moves in 3 different directions
• Keratinized stratified squamous epithelium,
papillae on dorsal surface (extra protection)

Fungiform: Taste Buds

Filiform: spikes, rough, traction for food, important for grooming (Rough cat tongue)

Moist stratified (non keratinized) squamous
epithelium, no papillae on ventral surface

Fungiform: spikes, rough, traction for food, important for grooming (Rough cat tongue)

Filiform: Taste buds

Moist stratified (non keratinized) squamous
epithelium, no papillae on ventral surface

Several pairs located on head and neck,
under tongue
– Parotid, mandibular or submandibular,
sublingual, zygomatic
– Contain amylase  starts chemical
digestion of starches, contains buffer
(ruminants)
– Mucous (thick), serous (watery) or mixed
– Ducts empty saliva into oral cavity to
lubricate food for chewing and swallowing

A space, not an organ (nasopharynx vs. oropharynx)
• Swallowing closes epiglottis over glottis to keep food
and saliva out of larynx and trachea and sending it into
esophagus
– Reflex triggered by food moving into pharynx
– Can be conscious

Several pairs located on head and neck,
under tongue
– Parotid, mandibular or submandibular,
sublingual, zygomatic
– Contain amylase  starts chemical
digestion of starches, contains buffer
(ruminants)
– Mucous (thick), serous (watery) or mixed
– Ducts empty saliva into oral cavity to
lubricate food for chewing and swallowing

A space, not an organ (nasopharynx vs. oropharynx)
• Swallowing closes epiglottis over glottis to keep food
and saliva out of larynx and trachea and sending it into
esophagus
– Reflex triggered by food moving into pharynx
– Can be conscious

Several pairs located on head and neck,
under tongue
– Parotid, mandibular or submandibular,
sublingual, zygomatic
– Contain amylase  starts chemical
digestion of starches, contains buffer
(ruminants)
– Mucous (thick), serous (watery) or mixed
– Ducts empty saliva into oral cavity to
lubricate food for chewing and swallowing

A space, not an organ (nasopharynx vs. oropharynx)
• Swallowing closes epiglottis over glottis to keep food
and saliva out of larynx and trachea and sending it into
esophagus
– Reflex triggered by food moving into pharynx
– Can be conscious

Muscular tube from pharynx to stomach
• Skeletal and/or smooth muscle
depending on species and area
• Lays flat, very muscular
• Will expand and layers will stretch
• Lumen enclosed with folds

Simple stomach (monogastric)
– Abomasum of ruminant similar
• Enlarged area at end of esophagus just caudal to diaphragm
• Glandular types determine regions
• Gastric folds: rugae

Several pairs located on head and neck,
under tongue
– Parotid, mandibular or submandibular,
sublingual, zygomatic
– Contain amylase  starts chemical
digestion of starches, contains buffer
(ruminants)
– Mucous (thick), serous (watery) or mixed
– Ducts empty saliva into oral cavity to
lubricate food for chewing and swallowing

A space, not an organ (nasopharynx vs. oropharynx)
• Swallowing closes epiglottis over glottis to keep food
and saliva out of larynx and trachea and sending it into
esophagus
– Reflex triggered by food moving into pharynx
– Can be conscious

Muscular tube from pharynx to stomach
• Skeletal and/or smooth muscle
depending on species and area
• Lays flat, very muscular
• Will expand and layers will stretch
• Lumen enclosed with folds

Simple stomach (monogastric)
– Abomasum of ruminant similar
• Enlarged area at end of esophagus just caudal to diaphragm
• Glandular types determine regions
• Gastric folds: rugae

Outer, same as visceral peritoneum

2 layers of muscle, longitudinal, outer layer, circular inner layer

Lose C.T. (areolar), glands, digestive enzymes, mucous

Innermost layer

– Epithelium lines lumen: Stratified squamous (usually

moist) in esophagus  simple columnar in rest (often in

projections or villi)

– Muscularis mucosae: small muscle layer

Outer, same as visceral peritoneum

2 layers of muscle, longitudinal, outer layer, circular inner layer

Lose C.T. (areolar), glands, digestive enzymes, mucous

Innermost layer

– Epithelium lines lumen: Stratified squamous (usually

moist) in esophagus  simple columnar in rest (often in

projections or villi)

– Muscularis mucosae: small muscle layer

Outer, same as visceral peritoneum

2 layers of muscle, longitudinal, outer layer, circular inner layer

Lose C.T. (areolar), glands, digestive enzymes, mucous

Innermost layer

– Epithelium lines lumen: Stratified squamous (usually

moist) in esophagus  simple columnar in rest (often in

projections or villi)

– Muscularis mucosae: small muscle layer

Outer, same as visceral peritoneum

2 layers of muscle, longitudinal, outer layer, circular inner layer

Lose C.T. (areolar), glands, digestive enzymes, mucous

Innermost layer

– Epithelium lines lumen: Stratified squamous (usually

moist) in esophagus  simple columnar in rest (often in

projections or villi)

– Muscularis mucosae: small muscle layer

Only significant in herbivores
– No glands
– Lined with keratinized stratified squamous epithelium
– Mixing, regurgitation
– Ruminant forestomach and other foregut fermenter
pouches = esophageal region

Near heart and near esophageal junction, most
cranial
– Not glandular, but has some non-complicated
mucous glands  protection from acid

Body
– Deep gastric pits/glands  most of secretion
– 3 cells
• Mucous cells  produce mucous  protection
from acid
• Chief cells  produce inactive pepsinogen
(proteolytic enzyme precursor)
• Parietal cells  produce HCl  lowers pH of
stomach to as low as 1.5  kills bacteria 
drops to proper pH to turn inactive pepsinogen
to active pepsin  breaks down protein

Pyloric sphincter joins stomach to small
intestine
• Dictates how much foodstuff enters the
duodenum
– Glands produce mucous, HCl, pepsinogen, and
• G cells  gastrin
– Stimulates HCl release when food present

Only significant in herbivores
– No glands
– Lined with keratinized stratified squamous epithelium
– Mixing, regurgitation
– Ruminant forestomach and other foregut fermenter
pouches = esophageal region

Near heart and near esophageal junction, most
cranial
– Not glandular, but has some non-complicated
mucous glands  protection from acid

Body
– Deep gastric pits/glands  most of secretion
– 3 cells
• Mucous cells  produce mucous  protection
from acid
• Chief cells  produce inactive pepsinogen
(proteolytic enzyme precursor)
• Parietal cells  produce HCl  lowers pH of
stomach to as low as 1.5  kills bacteria 
drops to proper pH to turn inactive pepsinogen
to active pepsin  breaks down protein