periodic acid Schiff base (PAS)

Stains carbohydrates. A tissue-stain in which 1,2-glycol groupings are 1st oxidized with periodic acid to aldehydes, which then react with sulfite leucofuschin reagent of Schiff & become colored red-violet. Strong staining occurs with polysaccharides such as glycogen & mucopolysaccharides of epithelial mucins, basement membrane & connective tissue.

References

Stedman's Medical Dictionary 26th ed, Williams & Wilkins, Baltimore, 1995