Mixed

Question 1

Cytoplasm become opaque and congeals into a netlike structure. (Imagine a mesh ball, making protein insoluble; aqueous/alcoholic sol’n will penetrate through the holes in the mesh ball).

• is this fixative type coagulant or non-coagulant ?

Answer 1

Coagulant fixative

Question 2

Does not disrupt the cytoplasm but transforms it into a transparent gel. ( imagine a ball of “jello”; aqueous sol’n would have difficulty penetrating jello).
Fixation of tissue protein is by cross-linking.

• is this a fixative type coagulant or non coagulant ?

Answer 2

Non coagulant

Question 3

Names all the coagulant fixatives

Answer 3

1. Ethanol
2. Methanol
3. Acetone
4. Mercuric
5. Chloride
6. Chromium
   6.Trioxide
7. Zinc salts
8. Picric acid

Question 4

Name all the non-coagulants fixatives

Answer 4

1. Formaldehyde
2. Glutaraldehyde
3. Osmium tetroxide
4. Potassium dichromate

Question 5

Tolerant fixative definition

Answer 5

How tolerant is a fixative on tissues, can it be left in sol’n for long period of time and not be destroyed or left in sol’n only for a few hours.

Question 6

Non-tolerant definition

Answer 6

When long exposure may make tissue hard and brittle and destroy some features

Question 7

Additive fixatives definition

Answer 7

Crosslink with proteins in cells, strengthening cell structure & insuring preservations

Additive fixative are non-coagulant

Question 8

Non-additive fixation definition

Answer 8

Organic compounds, acts on tissue without chemically combining with it.
- can cause shrinkage and harden if overexposed

Question 9

Additive fixatives

Answer 9

1.formaldehyde
2. Glutaraldehyde
3. Picric acid

Question 10

Non-additives fixatives

Answer 10

1. Acetone
2. Alcohols

Question 11

Fixatives best for nucleic acids

Answer 11

1.ethanol
2.acetic acid
3. Carnoy’s

Question 12

Lipids fixatives

Answer 12

1. Osmium tetroxide
2. Chromic acid

Question 13

Which fixative causes less shrinkage than any other fixatives ?

Answer 13

Formaldehyde

Question 14

What fixative causes brown black deposits seen on microscopic ?

Answer 14

AFH- acid formaldehyde Haematin- formalin pigment. (When sol’n is not buffered in pH drops)

Question 15

What happens when unbuffered formalin changes to formic acid ?

Answer 15

Creates pigment forming in bloody tissues

Question 16

Which fixatives is better at preserving glycogen?

Answer 16

Formol (10% alcoholic formalin)

Question 17

Which fixatives have a slow penetration rate

Answer 17

Glutaraldehyde

Question 18

Which fixative is used for EM (preserves ultrastructure)

Answer 18

Glutaraldehyde

Question 19

Which fixative is used for a secondary (post) fixative for EM samples

Answer 19

Osmium tetroxide

Question 20

Which fixative can be used to stain lipids in frozen sections

Answer 20

Osmium tetroxide

Question 21

What does osmium tetroxide preserves best ?

Answer 21

Cell membrane by combining with lipids making them insoluble.

Question 22

Which fixatives causes swelling in the tissue but when used with other fixative counteract their shrinkage effects.

Answer 22

Acetic acid

Question 23

Which fixative fixes well the nuclei ?

Answer 23

Acetic acid

Question 24

Which fixatives penetrates rapidly, leaving tissues soft but lyses red blood cells.

Answer 24

Acetic acid

Question 25

Which fixative can be used as a fixative and a stain ?

Answer 25

Picric acid

Question 26

Which fixative can decalcify small calcium deposits

Answer 26

Picric acid

Question 27

Which fixative will Leave tissue receptive to acid dyes (eosin) and can also be used as a supersaturated sol’n ?

Answer 27

Picric acid

Question 28

Which fixative preserves tissue antigenicity making retrieval procedures unnecessary for immunohistochemistry ?

Answer 28

Zinc salts

Question 29

Which fixative is commonly used for fixation of lymph bode and bone marrow tissues

Answer 29

Zinc salt

Question 30

Which fixative can be used as a substitute for mercury in the B-5 sol’n ?

Answer 30

Zinc salt

Question 31

Which fixative is a bifunctional aldehyde that reacts like in a similar manner to formaldehyde glyoxal

Answer 31

Glyoxal

Question 32

Which fixative can be a formalin substitute ?

Answer 32

Glyoxal

Question 33

Which fixative have a rapid action but cause brittleness in tissues. Is not used in automated processing schedule due to its volatility. Is also used as a dehydrating.

Answer 33

Acetone

Question 34

Which fixative denatures proteins by water replacement, cause shrinkage and is best used to preserve glycogen ?

Answer 34

Ethanol

Question 35

Which fixative is used to preserve glycogen but will cause distortion of nuclear and cytoplasmic detail.

Answer 35

Ethanol

Question 36

Which fixative is used as a fixative for blood films

Answer 36

Methanol

Question 37

Which fixative is used for cytology smears ?

Answer 37

95% ethanol

Question 38

Fixative for eyes, brain, lungs, muscles biopsies, testis

Answer 38

Neutral buffered formalin

Question 39

Fixative for lymphoid tissues

Answer 39

Neutral buffered formalin, B-5, B+

Question 40

Fixative for renal biopsies

Answer 40

Neutral buffered formalin, EM fixative, IF/IHC fixative

Question 41

Steps of tissue processing

Answer 41

1. Dehydration 2. Clearing 3. Wax infiltration 4. Embedding

Question 42

Dehydrating agents

Answer 42

1. Ethanol 2. Methanol 3. Isopropanol 4. Denatured alcohol

Question 43

Universal solvents

Answer 43

1. Dioxane 2. Tertiary butanol 3. Tetrahydrofuran