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Acetylation for the Periodic Acid-Schiff Reaction


For the Periodic Acid-Schiff Reaction

This procedure is used in the Periodic Acid-Schiff (PAS) reaction to block hydroxyl and amino groups. It does this by forming esters with them. As a consequence some carbohydrates fail to react with the Schiff’s reagent. This may be used as a means of identifying them, particularly if done in conjunction with other blocking procedures.


Acetic anhydride16mL
Pyridine, anhydrous24mL


Place dewaxed sections into the solution at the temperature specified for the time given.

Cartilage58°C6 hoursComplete
Cartilage25°C24 hoursComplete
Glycogen25°C6 hoursAlmost complete
Epithelial mucin25°C6 hoursComplete

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.