An improved histochemical method for distinguishing colonic acetylsialomucin from other epithelial mucins

A technical modification of the original histochemical methods for distinguishing human colonic acetylsialomucin from other epithelial mucins is described. The modification uses a naphthoic acid hydrazide-diazonium salt sequence in place of the original borohydride or blue Schiff treatments in the first stage of the staining procedure and a more dilute solution of periodic acid in the second stage. By these means, strongly contrasting staining of colonic acetylsialomucins in magenta red and all other mucins in dark blue may be consistently produced.