This procedure is also called saponification. It reverses the effects of acetylation and restores PAS 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: A) blocking of staining by acetylation, and B) restoration of staining by deacetylation.


Chemical Amount
Ethanol, absolute 30 mL
Distilled water 10 mL
Ammonia water, 28% 10 mL



  1. Celloidinise previously acetylated sections.
  2. Place into the solution in a sealed container at 37°C for 4-24 hours.
  3. Rinse well with 80% ethanol.
  4. Continue on with the staining method.
Tissue Temp Time State
Glycogen 37°C 4-6 hours restored
Intestinal mucins 37°C 4-6 hours restored
Basement membrane 37°C 16 hours restored
Brush borders 37°C 16 hours restored
Retinal rods 37°C 24 hours restored



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




Translate in
Google Translate