FIXATION LECT- 💡part 3

Formaldehyde/Formalin

37-40% aka 100% formalin

10% formalin

100 mL of 37-40% formaldehyde + 900 mL distilled water

10% formalin

Advantages: Cheap, easy to prepare and readily available. Recommended for mailing specimens since it is a tolerant fixative (you can leave the specimen in formalin for how long without causing any damage) and for colored tissue photography

10% formalin

Disadvantages: fumes are irritating, may cause allergic dermatitis on prolonged contact and may form brown pigment on blood containing tissues like spleen.

1 mm/hour

10% formalin- Penetration rate of formalin is

Kardasewitsch method

70% ethanol

28% ammonia water

Lillie’s Method

Hydrogen peroxide

28% ammonia water

Picric Acid Method

Saturated alcoholic picric acid

10% methanol

10% formalin Prolonged storage = precipitation of white paraformaldehyde, remedy for this is add

10% formol saline

diluted with distilled water and sodium chloride

10% formol saline

Classified as histochemical fixative

10% formol saline

Used for general post mortem tissues (autopsy) and for CNS tissue

10% Neutral Buffered Formalin

10% formalin with phosphate buffer

10% Neutral Buffered Formalin

Recommended for fixing tissue with iron pigments and elastic fibers

Formol Corrosive

Contains formaldehyde and mercuric chloride

Formol Corrosive

Recommended for lipids, neutral fats and phospholipids

Gendre’s solution

Composition: 95% ETOH, Picric acid, Glacial HAc with formaldehyde

Gendre’s solution

For fixing sputum specimens and for microincineration techniques

Glutaraldehyde

Recommended for enzyme histochemistry and Electron Microscopy

2.5%

solution is for small tissue fragments

4%

larger tissues less than 4 mm thick

electron microscopy

Karnovsky’s paraformaldehyde-glutaraldehyde solution and Acrolein are for

Glyoxal

Supplied as a 40% aqueous solution

Glyoxal

Fast acting fixative

Surgical specimens

are fixed within 4-6 hour

small biopsy specimens

within 45 min

MERCURIC CHLORIDE

Excellent for: trichrome staining

wash tissue with alcoholic iodine

MERCURIC CHLORIDE remedy

Zenker’s Fluid

It contains mercuric fluoride and glacial acetic acid

Zenker’s Fluid

Recommended for fixing liver, spleen, connective tissue fibers and nuclei

Zenker’s formol

It contains potassium dichromate and 40% formaldehyde

Zenker’s formol

Preserve pituitary glands, bone marrow and for other blood-containing organs

Zenker’s formol

a.k.a. Helly’s fluid

Heidenhain’s Susa

with TCA, Glac HAc & formalin

Heidenhain’s Susa

Recommended for preserving tumor skin biopsies

Heidenhain’s Susa

It contains TCA, glacial HAC and 40% formaldehyde

B5

With anhydrous sodium acetate

B5

For preserving bone marrow

Chromic acid

recommended for preserving carbohydrates

1-2%

Chromic acid

Potassium dichromate

preserves lipids and mitochondria

3%

Potassium dichromate

Regaud’s

aka Moller’s fluid

Regaud’s

For Chromatin, mitochondria, mitotic figures, Golgi bodies and RBC containing colloid tissues

Orth’s fluid

For early degenerative processes and tissue necrosis

Orth’s fluid

Rickettsia and other bacteria

LEAD FIXATIVES

For acid mucopolysaccharide and tissue mucin