Acetylation and Nitrosation of Tissue Amines in Histochemistry

Acetylation to prevent the reaction of 1,2 glycols to the periodic acid Schiff procedure was introduced into histochemistry by McManus and Cason (20) in 1950. Seligman (25) commented that amines would also be acetylated, which MacManus admitted, but stated that the saponi-fication by potassium hydroxide restored the reactivity of hydroxyls but would not decompose acetylated arnines. This statement has been widely accepted and various authors have used it for exclusion of amines as the reactive groups (6, 9, 10). It has further been stated that amines are more easily acetylated than glycols and that undiluted acetic anhydride or its fresh aqueous solutions