what does PAS stain
PAS staining is mainly used for staining structures containing a high proportion of carbohydrate macromolecules (glycogen, glycoprotein, proteoglycans), typically found in e.g. connective tissues, mucus, the glycocalyx, and basal laminae.hese aldehydes then react with the Schiff reagent to give a purple-magenta color. A suitable basic stain is often used as a counterstain. PAS diastase stain (PAS-D) is PAS stain used in combination with diastase, an enzyme that breaks down glycogen.