Fixation (Part 3)

Question 1

Used to preserve brain tissue for diagnosis of rabies

Answer 1

Acetone and Carnoy’s fluid

Question 2

Must be used at ice cold temperature
Fixative and dehydrating agent for phosphatases and lipases

Answer 2

Acetone

Question 3

Disadvantages of acetone

Answer 3

• Volatile (evaporates easily)
• Dissolves fat

Question 4

Considered as the most rapid fixative
For fixing chromosomes and lymph glands

Answer 4

Carnoy’s fluid

Question 5

Excellent for glycogen demonstration

Answer 5

Picric Acid Fixatives

Question 6

Why is picric acid considered as versatile reagent?

Answer 6

• Can be used as decalcifying agent (because it is an acid)
• Can be used as a stain
• Can also be used as a fixative

Question 7

Disadvantage of Picric Acid

Answer 7

Can impart a yellow color

Question 8

A picric acid used to preserve embryos, pituitary biopsies & endometrial curettings but contraindicated for kidney structures

Answer 8

Bouin’s fluid

Question 9

Bouin’s fluid is not compatible with what stain?

Answer 9

Feulgen’s stain

Question 10

Used for touch preparations

Answer 10

95% Isopropyl Alcohol

Question 11

Soldifies at 17degC
A nuclear fixative (contraindicated for cytoplasmic fixation)
Often used in combination with other fixatives to form a compound fixative

Answer 11

Glacial Acetic Acid

Question 12

Used for mucopolysaccharides and nuclear protein

Answer 12

Newcomer’s fixative

Question 13

Examples of Fixatives for Electron Microscopy (EM) (3)

Answer 13

1. Osmium Tetroxide
2. Glutaraldehyde
3. Paraformaldehyde

Question 14

Can be used for myelin and peripheral nerves (neurologic structures)
Disadvantage: Slow in Action

Answer 14

Osmium Tetroxide

Question 15

• Method of fixation that uses chemical fixatives such as formalin, zenker’s, etc
• Immersing the specimen in the fixative

Answer 15

Chemical Fixation

Question 16

The routine tissue fixative

Answer 16

10% formalin

Question 17

Method of fixation that uses heat fixation, microwave technique etc.
Can be done in preparing frozen sections

Answer 17

Physical Fixation

Question 18

• Fixation method that involves thermal coagulation of proteins
• Used in micro, in bacte to prepare bacterial smears

Answer 18

Heat fixation

Question 19

Fixative volume in Museum preparations

Answer 19

50 to 100 time the volume of the specimen

Question 20

Used to wash out excess amount of Mercuric fixaitves

Answer 20

Alcoholic Iodine

Question 21

Used to wash out excess amount of picric acid fixatives

Answer 21

50-70% alcohol

Question 22

Often used in conjunction with other fixatives to produce a compound fixative other than Glacial Acetic Acid

Answer 22

TCA (trichloro acetic acid

Question 23

A weak and slow decalcifying agent

Answer 23

TCA