Stage of prenatal development:

3rd week to 8th week

Stage of prenatal development:

8th week to birth

Conception occurs when a sperm cell penetrates and fertilizes an egg cell.

__________________ occur when two separate eggs are ovulated.

May be of different sexes.

__________________ occur when a single egg is fertilized but dividing cells break into two groups and develop into two individuals. Genetically identical (clones)

Parts of the Zygote:

inner layer of cells that develops during the germinal period

–Later develops into embryo

Parts of the Zygote:

outer layer of cells that develops during germinal period

–Provides embryo nutrition and support

•Implantation anywhere outside the uterus is called an __________________ .

Implantation inside the uterus is called an __________________ .

•As early as 8 -12 days after fertilization, the blastocyst begins to secrete _______________.

•It keeps the corpus luteum active until the placenta can produce estrogens and progesterone.

•The presence of _____________ is the basis for pregnancy tests.

•Protects Fetus

•Controls Temperature

•Supports Symmetrical Growth

•Prevents Adherence to amnion

•Allows Movement

•Source of oral fluid

•Acts as a excretion-collection repository.

Connecting link between fetus and placenta.

•Transports oxygen and nutrients to fetus from the placenta and returns waste products from the fetus to the placenta.

•Contains: 2 arteries and 1 vein supported by mucoid material (wharton’s jelly) to prevent kinking and knotting.

•Contains NO pain receptors.

Produce protein hormones:

•Human chorionic gonadotrophin (HCG)- 8-10 days past conception, is basis for pregnancy test

•Progesterone

•Estrogen

•Human Placental Lactogen.

•Sieve/filter – allows smaller particles through and holds back larger molecules. Passage of materials in either direction is effected by:

–Diffusion: gases, water, electrolytes

–Facilitated transfer: glucose, amino acids, minerals.

Pinocytosis: movement of minute particle.

The Embryonic Period:

__________________ organ formation.

The Embryonic Period:

__________________ inner layer of cells form digestive and respiratory systems

The Embryonic Period:

__________________ outermost layer of cells form skin parts, nervous system, and sensory receptors

The Embryonic Period:

__________________ middle layer of cells form bones, circulatory system, muscles, excretory and reproductive systems