METALLIC FIXATIVES

Mercuric chloride

Most common metallic fixative

Mercuric chloride

Tissue photography - penetrates and hardens tse rapidly

Mercuric chloride

Trichome staining is excellent

Mercuric chloride

Banned worldwide due to extreme toxicity; cell shrinkage (rem: add acid)

Mercuric chloride

Forms black precipitates of Mercury, expt: Susa (rem: Dezenkerization)

Zenker's fluid

HgCl2 + glacial acetic acid

Zenker's fluid

General fixative

Zenker's fluid

Acts as mordant (special staining possible)

Zenker's fluid

Recommend for trichome staining

Helly’s

HgCl2 + 40% strong formalin

Helly’s

Pituitary gland, BM, blood-containing organs (liver and spleen)

Helly’s

Forms brown pigments (rem: picric acid/NaOH)

Heidenhain’s

Good for skin tumor biopsy

Heidenhain’s

Min. Cell shrinkage and tissue hardening due to counter-balance effect (mercury = shrinkage; acid= swelling)

Heidenhain’s

Weigerts elastic staining is not possible

Heidenhain’s

Excellent cytologic fixative

B-5

Rapid fixation (1.5 to 2 hrs only)

B-5

Bone marrow biopsies

B-5

Hematopoietic and lymphoid tissue

Schaudinn

Loose cells smears

Chromic acid

Preserves carbs; precipitates proteins

Regaud

Chromatin, mitochondria, mitotic figures, golgi bodies, RBC, and colloid

Regaud’s

Prolonged fixation = blackening of tissue pigment (rem: H20 before dehy)

Regaud

Produces sub-oxidation ppt

Orth’s

Early degenerative and mecrosis

Orth’s

Rickettsiae and other bacteria

Orth’s

Preserves myelin

Potassium dichromate

Preserves lipids and mitochondria

Potassium dichromate

No cytoplasmic ppt

Potassium dichromate

Corrosive; no skin contact

Lead

Preserves acid mucopolysaccharides

Lead

Prolonged standing = insoluble lead carbonate (rem: acetic acid drops)