De-acetylation

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.

Solution

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

 

Procedure

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

 

Reference

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