Fixation (I: Simple Fixatives)

Question 1

Used in the make up of Helly’s fluid

Answer 1

Formaldehyde (HCHO)

Question 2

Purest conc of formaldehyde

Answer 2

40% by weight gas

Question 3

Routine formalin solution conc

Answer 3

10%

Question 4

Fixation time using formaldehyde

Answer 4

12-24 hours

Question 5

Causes turbidity in commercial formaldehyde after prolonged storage

Answer 5

Paraformaldehyde

Question 6

Fixative that preserves fat and mucin

Answer 6

Formaldehyde

Question 7

Best fixative for nervous tissue

Answer 7

Formaldehyde

Question 8

Fixative that preserves cellular and plasma protein better than formaldehyde

Answer 8

Glutaraldehyde

Question 9

Glutaraldehyde conc for small fragments and small needle biopsies

Answer 9

2.5%

Question 10

Glutaraldehyde conc for large tissues not exceeding 4 mm

Answer 10

4%

Question 11

Fixation time for 2.5% glutaraldehyde

Answer 11

2-4 hours

Question 12

Fixation time for 4% glutaraldehyde

Answer 12

12-24 hours

Question 13

A polymer of formaldehyde that is a white powder

Answer 13

Paraformaldehyde

Question 14

Conc and temp of paraformaldehyde use

Answer 14

4% at 4°C

Question 15

Fixative for thin and ultrathin sections for plastic embedding

Answer 15

Paraformaldehyde

Question 16

Fixative that allows better staining of nuclei and CT

Answer 16

Mercuric chloride (HgCl2)

Question 17

Fixative recommended for renal, fibrin, and CT

Answer 17

Mercuric chloride

Question 18

Fixative that corrodes metals except nickel

Answer 18

Mercuric chloride

Question 19

Conc of chromate fixatives used

Answer 19

1-2%

Question 20

Fixatives that are strong oxidizing agents and should not combine with reducing agents such as alcohol and formalin

Answer 20

Chromate fixatives

Question 21

Fixative that is a strong protein precipitant

Answer 21

Chromate fixatives

Question 22

Preserves carbohydrates

Answer 22

Chromate fixatives

Question 23

Forms a precipitate of insoluble suboxide

Answer 23

Chromate fixatives

Question 24

Poor for glycogen fixation

Answer 24

Chromate fixatives

Question 25

Conc of potassium dichromate used

Answer 25

3%

Question 26

A strong fixative for certain lipids

Answer 26

Potassium dichromate

Question 27

Preserves mitochondria

Answer 27

Potassium dichromate

Question 28

Conc of lead fixatives used

Answer 28

4%

Question 29

Used mainly for mucopolysaccharides

Answer 29

Lead fixatives

Question 30

Chemical name of picric acid

Answer 30

2,4,6-trinitrophenol

Question 31

Best fixative for glycogen

Answer 31

Picric acid fixatives

Question 32

Temp at which acetic acid fixatives are used

Answer 32

-40°C

Question 33

Fixes and precipitates nucleoproteins

Answer 33

Acetic acid fixatives

Question 34

Precipitates chromosomes and chromatin material

Answer 34

Acetic acid fixatives

Question 35

Useful for nuclear studies

Answer 35

Acetic acid fixatives

Question 36

Destroys mitochondria and golgi elements

Answer 36

Acetic acid fixatives

Question 37

Temp at which acetone fixatives are used

Answer 37

-40°C

Question 38

Used only in enzyme(phosphatase & lipase) studies

Answer 38

Acetone fixatives

Question 39

Used for fixing brain tissue for rabies

Answer 39

Acetone

Question 40

Used for rapid denaturing and precipitation of proteins by destroying hydrogen and other bonds

Answer 40

Alcohol fixatives

Question 41

Conc of alchol fixatives used

Answer 41

70-100% (lower conc lyses cells)

Question 42

Fixes conjugate fats and lipids permanently by making them insoluble during subsequent treatment with alcohol and xylene

Answer 42

Osmium tetroxide fixative (osmic acid)

Question 43

Satisfactory fixatives for routine paraffin sections, frozen sections, and for electron microscopy

Answer 43

Aldehyde fixatives