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De-acetylation for the Periodic Acid-Schiff Reaction


For the Periodic Acid-Schiff Reaction

This procedure is also called saponification. It reverses the effects of acetylation and restores Periodic Acid-Schiff positivity. However, this is not absolute, and proceeds at different rates for different compounds. It may therefore be used to identify compounds based on double criteria:

  • Blocking of staining by acetylation, and
  • Restoration of staining by deacetylation


Ethanol, absolute30mL
Distilled water10mL
Ammonia water, 28%10mL


  1. Celloidinize previously acetylated sections.
  2. Place into the solution in a sealed container at 37°C for 4-24 hours.
    Glycogen37°C4-6 hoursRestored
    Intestinal mucins37°C4-6 hoursRestored
    Basement membrane37°C16 hoursRestored
    Brush borders37°C16 hoursRestored
    Retinal rods37°C24 hoursRestored
  3. Rinse well with 80% ethanol.
  4. Continue on with the staining method.

Safety Note

Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.


  1. Lillie, R.D., (1954)
    Histopathologic technique and practical histochemistry Ed.2
    Blakiston, New York, USA