Histology

Question 1

Its mode of action differs above and below pH 3.75

Answer 1

Potassium Dichromate

Question 2

If acidic, (unbuffered), a dark brown precipitate may form in vascular tissue.

Answer 2

Formalin

Question 3

Its use results in layer fixation and causes pronounced shrinkage.

Answer 3

Mercuric Chloride

Question 4

It has a fast penetration rate but fixation is slow.

Answer 4

Formalin

Question 5

This will fix lipids and blacken them microscopically.

Answer 5

Osmium tetroxide

Question 6

It is used almost exclusively for electron microscopy, as it preserves the ultrastructure.

Answer 6

Glutaraldehyde

Question 7

If concentrated form is purchased it must be diluted to 10%(w/v) for use

Answer 7

Formalin

Question 8

Addition of methanol can reduce polymerization of this fixative.

Answer 8

Formalin

Question 9

Its precipitate is difficult to remove but can be reduced with 1% acid alcohol.

Answer 9

Potassium Dichromate

Question 10

Yellow precipitate can be prevented by washing tissue prior to dehydration.

Answer 10

Potassium Dichromate

Question 11

Its precipitate can be removed using alcoholic iodine followed by sodium thiosulfate.

Answer 11

Mercuric Chloride

Question 12

Used as a component of compound fixatives in the fixation of blood films, cytology smears and enzymes for histochemistry.

Answer 12

Ethyl Alcohol

Question 13

It forms a black precipitate throughout the tissue.

Answer 13

Mercuric Chloride

Question 14

It is extremely volatile and can fix nasal mucosa within minutes of exposure.

Answer 14

Osmium tetroxide

Question 15

It is extremely toxic affecting the CNS and can cause acute nephritis.

Answer 15

Mercuric Chloride

Question 16

Tissues are left soft if used alone, so it is used as part of a compound fixative.

Answer 16

Potassium Dichromate