Fixatives Aldehyde

Question 1

● Gas produced by oxidation of methanol
● most common are the routine fixative that we are using for histopathologic techniques
● Usually buffered to pH 7 with phosphate buffer

Answer 1

FORMALDEHYDE (FORMALIN)

Question 2

Saturated formaldehyde + 10% NaC

Answer 2

10% FORMOL-SALINE

Question 3

● Best general tissue fixative
● Best for iron-containing pigments and elastic fibers which do not stain well after Susa, Zenker or Chromate fixation

Answer 3

10% NEUTRAL BUFFERED FORMALIN

Question 4

● Saturated aq. Mercuric chloride + 40% Formaldehyde
● Recommended for routine post mortem tissues; Silver Reticulum staining methods

Answer 4

FORMOL-CORROSIVE (FORMOL MERCURIC
CHLORIDE)

Question 5

● Has 95% ETOH, Picric acid, and GHAc
● ADV: good for microincineration techniques, fixes SPUTUM

Answer 5

GENDRE’S (ALCOHOLIC FORMALIN)

Question 6

For gastrointestinal (GI) tissues, prostate biopsies, and bone marrow (BM)

Answer 6

HOLLANDE’S

Question 7

● ADV: more pleasant and less irritating compared to formalin
● DADV: less stable and more expensive than formalin

Answer 7

GLUTARALDEHYDE

Question 8

● Polymer of formalin
● Powder in form, used in 4%
● Plastic embedding
● For ultrathin and electron microscopy

Answer 8

PARAFORMALDEHYDE

Question 9

● Acrolein in glutaraldehyde or formalin
● Purpose: for Electron Histochemistry and Electron Immunocytochemistry

Answer 9

KARNOVSKY’S PARAFORMALDEHYDE/
GLUTARALDEHYDE

Question 10

● ADV: NO SMUDGING of nuclei and distortion of staining compared with formalin
● DADV reduced staining capacity
→ Remedy: increase staining time

Answer 10

40% AQUEOUS GLYOXAL