OSMIC ACID AND HEAT FIXATIVES

Question 1

Pale yellow powder in water (6% in 20°C)

Answer 1

OSMIC ACID FIXATIVES

Question 2

Ultrathin section in Electron Microscopy

Disadvantage: very expensive, very volatile, inhibits hematoxylin

Answer 2

OSMIC ACID FIXATIVES

Question 3

OSMIC ACID FIXATIVES

Tissue-to-fixative ratio:

Answer 3

1:5

Question 4

• Nuclear fixative (_______)
• Most common osmic acid fixative

• Effect: permanently fixes fat
• Advantage: needs less amount of fixative

Answer 4

Flemming’s Solution w/ GAC

24 - 48hrs

Question 5

• Cytoplasmic Fixative (_____)

Answer 5

Flemming’s Solution w/o GAC

24 - 48hrs

Question 6

• Incorporated into compound fixatives
• Marked swelling effect on tissues
• Poor penetration thus for small pieces of tissues or bones
• Weak decalcifying agent, this has softening effect on dense fibrous tissues

Answer 6

Trichloroacetic Acid

Question 7

• Use at ice cold temperature(_____)
• For water-diffusible enzymes (Phosphatase, Lipase)

Answer 7

Acetone

(-5 to 4°C)

Question 8

• Fixes brain tissue (for rabies)
• Disadvantage: Dissolves fat, evaporates rapidly

Answer 8

ACETONE

Question 9

• Involves thermal coagulation of tissue proteins for rapid diagnosis

Answer 9

HEAT FIXATION

Question 10

• Frozen tissue sections & bacteriologic smears
• 10 - 15mins thickness of tissue

Answer 10

HEAT FIXATION

Question 11

• Increases movement of molecules to accelerate fixation, staining, and decalcification

Answer 11

• Microwave Technique

Question 12

• Advantage: Can preserve neurochemical substances of tissues
• Disadvantage: Cannot penetrate tissues that are
10 - 15mm in thickness

Answer 12

HEAT FIXATION

Question 13

• Optimum temperature for Heat Fixation

Answer 13

45° - 55°C