WorksheetsPC1.2 Compare different types of fixatives and their application
Total questions: 20
Worksheet time: 10mins
What is the main purpose of tissue fixation in histology?
To stain tissue
To preserve tissue structure and prevent decay
To remove water from tissue
To cut tissue into thin sections
Which process stops autolysis and putrefaction in tissue samples?
Embedding
Fixation
Clearing
Sectioning
Which property is MOST important for a good chemical fixative?
Bright color
Fast evaporation
Ability to preserve tissue morphology
Ability to dissolve tissue
Which fixative is commonly used as 10% neutral buffered formalin?
Glutaraldehyde
Alcohol
Formaldehyde
Osmium tetroxide
Why must formaldehyde be handled in a fume hood?
It stains skin
It is highly toxic and a respiratory poison
It evaporates slowly
It fixes tissue too fast
Which tissue component is POORLY preserved by formaldehyde?
Proteins
Nucleic acids
Lipids
Carbohydrates
How does formaldehyde preserve tissue structure?
By dissolving proteins
By freezing tissue
By forming cross-links between proteins
By removing lipids
Why is glutaraldehyde preferred for electron microscopy?
It is inexpensive
It penetrates tissue quickly
It preserves fine ultrastructural details
It does not cross-link proteins
What is a key limitation of glutaraldehyde fixation?
Poor nuclear preservation
Very slow tissue penetration
Causes tissue swelling
Poor morphology preservation
Mercuric-based fixatives are BEST suited for which tissues?
Nervous tissue
Muscle tissue
Hematopoietic tissues like bone marrow
Skin tissue
Which artefact is commonly seen with unbuffered formalin?
Tissue swelling
Acid formaldehyde hematin pigment
Yellow staining
Protein loss
What color does formalin pigment usually appear under the microscope?
Blue
Red
Brown-black
Green
Which fixative reacts with unsaturated lipids and makes them electron-dense?
Alcohol
Acetic acid
Osmium tetroxide
Picric acid
Why is osmium tetroxide considered extremely hazardous?
It explodes easily
It damages DNA
It can cause blindness by damaging the cornea
It causes tissue shrinkage
Which fixative is classified as a non-additive, protein-denaturing fixative?
Formaldehyde
Alcohol
Mercuric chloride
Glutaraldehyde
Fixation prevents tissue degeneration caused by ________ and ________.
autolysis and putrefaction
dehydration and swelling
coagulation and necrosis
cross-linking and denaturation
Formaldehyde preserves tissue by forming ________ bridges between protein molecules.
methylene
hydrogen
disulfide
ionic
Brown-black deposits caused by unbuffered formalin are called ________ ________ ________.
acid formaldehyde hematin
formalin pigment
melanin granules
hemosiderin deposits
For proper fixation, tissue thickness should ideally be about ________ mm.
1
2
3
5
Fixatives are usually considered enzyme ________ because they stop tissue breakdown.
activators
inhibitors
cofactors
poisons
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