Periodic acid-Schiff (PAS) reaction​

Wolf D. Kuhlmann

Division of Radiooncology, Deutsches Krebsforschungszentrum, 69120 Heidelberg, Germany

The periodic acid-Schiff (PAS) reaction to demonstrate the presence of 1,2-glycol groupings is one of the most widely used histochemical methods. When tissue sections are treated with periodic acid, glycols are oxidized to aldehydes. After reaction with Schiff’s reagent (the main components are pararosaniline and sodium metabisulfite), a pararosaniline adduct is released that stains the glycol containing elements in the tissue section pink to red. A number of cellular elements may be demonstrated with the PAS reaction, e.g. glycogen, basement membranes sulfo- and sialomucins, neutral mucosubstances.