Fixation and Fixatives: Roles and Functions

Definition

Functions

Factors

Fixating Agents used in Histopathology

physiochemical process in which cells
or tissues are fixed chemically

Making tissue firm

Help make the tissue more easily permeable
for subsequent reagents

Preventing osmotic damage of tissues

emphasizing the
dissimilarity in refractive index

Conserving the association in between cells and extracellular substances

Prevent autolysis (enzymes attack) and putrefaction (bacterial attack) of tissues.

Temperature

Concentration

Length of fixation

Size

Osmolarity

Glutaraldehyde

Ethanol and Methanol

Formaldehyde or Formalin

Acetone

Mercuric Chloride

Glyoxal

Osmium Tetroxide

Acetic Acid

Potassium Dichromate

Bouin’s Fixative

Acrolein

Genipin

4- to 6-mm-thick

Prevent swelling or shrinkage of the tissue

0°to 4°C

Fixative agents need prolonged time for fixation if concentration is low. If concentrations of fixing agent are high, it
results in damaging of cellular structures as well as obliterated enzyme activities.

overnight fixation is sufficient