Fixation Part 4

Preserves carbohydrates; precipitates all protein

Chromic Acid 1-2%

For chromatin, mitochondria, mitotic figures, golgi bodies, RBC and colloid containing tissues

Regaud’s / Muller’s Fluid

DADV: prolonged fixation may lead to blackening of tissue pigment.

■ Remedy: Wash in running tap H2O before dehydration

Regaud’s / Muller’s Fluid

Study of early degenerative processes and necrosis; Rickettsiae and other bacteria

Orths’ Fluid

Preserves myelin

Orths’ Fluid

Preserves lipids & mitochondria at pH 4.5 to 5.2; cytoplasm, chromatin and chromosome are fixed

Potassium Dichromate

Corrosive, thus avoid skin contact

Potassium Dichromate

Preserves acid mucopolysaccharide

LEAD FIXATIVES

DADV: Prolonged standing → formation of insoluble lead carbonate

○ Remedy: add drops of acetic acid to dissolve residue

LEAD FIXATIVES

Normally used in strong aqueaous solution (1%)

Glycogen demonstration

Highly explosive when dry

○ Remedy: add distilled H2O or 0.5% - 1% saturated alcoho

PICRIC ACID FIXATIVES

Yellowing effect

○ Remedy: immerse in Li2CO3 with 70% ROH 🡪 water 🡪 70% ethanol 🡪 5% Na thiosulfate 🡪 water

PICRIC ACID FIXATIVES

For embryo and pituitary biopsies, and tissues to be stained with Masson’s Trichrome

Bouin’s

ADV: minimum cell shrinkage and tissue hardening due to counterbalance effect of glacial HAc (swelling) and picric acid (shrinking)

DADV: poorly penetrates large tissue, thus limited to small fragments of tissues

Bouin’s

○ Better and less messy than Bouin’s

Brasil’s Alcoholic Picroformol

○ Incorporated in compound fixatives

○ Solidifies at 17ºC

Glacial Acetic Acid

○ Important for nuclear fixatives (precipitates nucleoproteins, chromatins)

○ Destroys mitochondria and Golgi elements, thus not for cytoplasmic fixation

Glacial Acetic Acid

ADV: good for glycogen

DADV: dissolves Fats and Lipoproteins

ALCOHOL FIXATIVES

Causes polarization of glycogen (granules will move towards the poles or ends of the cells)

ALCOHOL FIXATIVES

Effect: rapidly denatures and precips CHONs, preserves nuclear stains

ALCOHOL FIXATIVES

Most rapid tissue fixative (1-3 hrs)

Carnoy’s Fluid

Fixing brain tissues for rabies diagnosis

Carnoy’s Fluid

Fixes Nissl granules and cytoplasmic granules

Carnoy’s Fluid

Enzyme studies; does not fix but preserves glycogen

Ethanol (70 - 100%)

Dry and wet smears, Bone Marrow smears, bacterial smears

Methanol / Wood Alcohol (100%)

Touch prep smears to be Wright-stained

Isopropanol

For mucopolysaccharide (12-18 hrs)

Newcomer’s Fluid

For sputum (4 - 18hrs)

Gendre’s (Alcoholic Formalin)