All About Fixatives

Question 1

Satisfactory ph

Answer 1

Ph 6-8

Question 2

Fixation temp of:
Tissue processors?
Electron microscopy and histochemistry?
Urgent biopsy specimens?
Tissue with tuberculosis?

Answer 2

40C
0-4C
60C
100C

Question 3

Thickness of section
Electron microscopy?
Light microscopy?

Answer 3

1-2 mm^2

2 cm^2

Question 4

Brain is suspended whole in what formalin?

Answer 4

10% buffed formalin for 2-3 weeks

Question 5

Osmolality that gives the best result?

Answer 5

Slightly hypertonic solution (400-450 mOsm)

Question 6

Concentration usually used for
Formalin?
Formaldehyde?

Answer 6

10%

3%

Question 7

Volume of fixative to tissue

Answer 7

20:1

Question 8

Fixation time for formalin

Answer 8

24 hrs

Question 9

Prolonged fixation May cause?

Answer 9

• shrinkage

- gardening severely inhibit enzyme activity and immunological reactions

Question 10

Duration of fixation for electron microscope?

Answer 10

3 hrs

Question 11

Penetration rate of formalin

Answer 11

1 mm/hr (slows down as it goes deeper)

Question 12

Fixation time an be cut down by using?

Answer 12

Heat, vacuum, agitation or microwave

Question 13

Recommended size of tissue?

Answer 13

2 cm^2 and no more than 4mm thick

Question 14

All tissues can be cut and trimmed without prior fixation except?

Answer 14

Brain

Question 15

T/F

Osmium inhibits hematoxylin staining

Answer 15

True

Question 16

Fixatives made up of only 1 component

Answer 16

Simple fixatives

Question 17

Fixatives made up of two or more fixatives?

Answer 17

Compound fixatives

Question 18

Name the simple fixatives

Answer 18

MALH

Metallic
Aldehydes
Lead
Heat

Question 19

Types of fixatives according to action?

Answer 19

• microanatomical

- cytological

Question 20

Fixative used for lipid

Answer 20

Fixatives containing:

• mercuric chloride
• potassium dichromate

Question 21

Used for glycogen fixation?

Answer 21

Alcoholic fixatives

Question 22

Used for protein fixation

Answer 22

• neutral buffered formol saline

- formaldehyde Vapors

Question 23

Type of fixatives that are satisfactory for routine paraffin sections

Answer 23

Aldehyde fixatives

Question 24

Ideal size of specimen

Answer 24

3mm

-should not be more than 4mm think

Question 25

T/F

👆🏻temp = 👆🏻rate of diffusion = 👆🏻 rate of chemical rxn

Answer 25

True

Question 26

Fixatives penetrate by?

Answer 26

Diffusion

Question 27

Highly polymerised form of formaldehyde?

Answer 27

Paraformaldehyde

Question 28

Alcohol fixatives conc range?

Answer 28

60-100

-less conc will lyse the cell

Question 29

Methanol 100%

Answer 29

Can fix: dry and wet smears, blood smears, bone marrow tissues

Question 30

Chemicals that fixes and dehydrates at the same time

Answer 30

Methanol

Acetone