fixation

10% Neutral Buffered Formalin

What is the most common Fixative used in Histopathology section?

OVER FIXATION

What is the cause of the shrinkage and sweeling of cells and tissue structure?

fixation

FIRST and MOST CRITICAL step of tissue processing

: Preserve the morphologic and chemical integrity of the cell

Primary objective for fixation

Harden and protect tissue from trauma.

secondary objective for fixatopm

10-20:1

Recommended volume : 10-20:1

10-25:1

Traditional method volume

50-100:1

museum prep volume

5-10:1

osmium tetroxide volume

7

ph

40c

Most tissue processor temp

0-4C

Electron Microcopy/Histochem samples temp

60C

rapid formalin temp

room temp

mast cell temp

3%

glutaraldehyde routine concen

0.25%

electron microscopy concen

37% to 40%

Commercial or stock solution: __ formaldehyde

Sodium dihydrogen phosphate Disodium hydrogen phosphate Distilled water 40% formaldehyde

compo of 10% formalin

20-30 mins

Ideal time to perform fixation:

physical, chemical

classification of fixatives

10% Formol Saline

For CNS tissues

o Advantage: Preserves enzymes and

nucleoproteins, demonstrates fats and mucin

o Disadvantage: slow fixative

10% buffered Neutral Formalin

For post-mortem and research specimen

o Advantage: Best fixative for tissue containing

iron pigments

o Disadvantage: It is longer to prepare.

Formal Corrosive

For routine post-mortem tissue

o Adv: Penetrates small tissues

o Disadv: Forms mercuric chloride deposits

glutaraldehyde

For electron microscopy

o Adv: It preserves cellular structures

o Disadv: It is more expensive

chloride

Most common metallic fixative

o May produce black granular deposits on tissues

chromate

Preserves chromatin tissue

lead fixative

For acid mucopolysaccharide

zenker formol

Adv: Excellent for pituitary gland, bone

marrow, spleen and liver

▪ Disadv: Brown pigments are produced

▪ Brown pigments can be dissolved in

saturated picric acid or NaOH.

chromate

preserves mitochondria

methyl alcohol

For dry and wet smears

isopropyl alcohol

o For fixing touch preparations

ethyl alcohol

70-100%

acetone

Fixes brain tissues for the diagnosis of rabies

trichloroacetic acid

Both a fixative and decalcifying agent

flemming's

For nuclear structure

Flemming's with acetic acid

For cytoplasmic structures

direct flaming

for bacterial smear

45-55C

microwave temp fixation

alcian blue

For acid mucopolysaccharide