LESSON 2: FIXATION (2)

Question 1

white precipitate due to prolonged storage

Answer 1

Paraformaldehyde

Question 2

what can removed paraformaldehyde?

Answer 2

10% methanol

Question 3

▪ central nervous tissues and general post-mortem tissues for histochemical examination

▪ ideal with most stains including silver impregnation

▪ duration of fixation: more than 24 hours (slow fixative)

Answer 3

10% Formol-Saline

Question 4

▪ preservation and storage of surgical, post-mortem and research specimens
▪ best fixative for frozen sections
▪ best fixative for iron pigments and elastic fibers

Answer 4

10% Neutral Buffered Formalin

Question 5

▪ routine post-mortem tissues
▪ for lipids, especially neutral fats and phospholipids
▪ no need for washing-out

Answer 5

Formol-Corrosive

Question 6

▪ used to fix sputum
▪ for the demonstration of immunoperoxidase activity

Answer 6

Alcoholic Formalin

Question 7

▪ made up of two formaldehyde residues linked by three carbon chains
▪ used in conjunction with osmium tetroxide
▪ Fixation time: 1⁄2 hour to 2 hours

Answer 7

Glutaraldehyde

Question 8

✓ most common metallic fixative
✓ tissue photography
✓ tissues contain black precipitates of mercury (except Susa)

Answer 8

Mercuric Chloride

Question 9

fixing small pieces of liver, spleen, connective tissues fibers and nuclei

Answer 9

Zenker’s Fluid

Question 10

pituitary gland, bone marrow and blood containing organs

Answer 10

Zenker-formol

Question 11

for tumor biopsies

Answer 11

Heidenhain’s Susa Solution

Question 12

for bone marrow biopsies

Answer 12

B-5 Fixative

Question 13

preserves carbohydrates

Answer 13

Chromic Acid

Question 14

preserves lipids and mitochondria

Answer 14

Potassium Dichromate

Question 15

demonstration of chromatin, mitochondria, mitotic figures, Golgi bodies, RBC and colloid-containing tissues

Answer 15

Regaud’s Fluid

Question 16

✓ study of early degenerative processes and tissue necrosis
✓ demonstrates Rickettsia and other bacteria

Answer 16

Orth’s Fluid

Question 17

demonstration of acid mucopolysaccharides

Answer 17

Lead Fixatives

Question 18

Picric acid is soluble to?

Answer 18

Water

Question 19

fixation of embryos and pituitary biopsies

Answer 19

Bouin’s Solution

Question 20

fixative for glycogen

Answer 20

Brasil’s Alcoholic Picroformol Fixative

Question 21

fixation of nucleoproteins

Answer 21

GLACIAL ACETIC ACID

Question 22

Preserves but does not “fix” glycogen granules

Answer 22

95 % Ethanol

Question 23

For dry and wet smears, blood and bone marrow samples

Answer 23

Methanol

Question 24

for touch preparations

Answer 24

Isopropyl alcohol (95%)

Question 25

▪ most rapid fixative
▪ for chromosomes, lymph glands, urgent biopsies and brain tissue for the diagnosis of rabies

Answer 25

Carnoy’s fluid

Question 26

demonstration of mucopolysaccharides and nucleoproteins

Answer 26

Newcomer’s

Question 27

Permanently fixes fats and recommended for fixing nuclear structures

Answer 27

Flemming’s (chrome-osmium HAc)

Question 28

For cytoplasmic structures

Answer 28

Flemming’s w/o acetic acid

Question 29

may also be used as a weak decalcifying agent

Answer 29

TRICHLOROACETIC ACID

Question 30

✓ use at cold temperature (-5 to 4
oC)
✓ fixation of brain tissues for rabies diagnosis

Answer 30

ACETONE