There are many uses for the PAS stain. One of the most common is the demonstration of fungus as well as the demonstration of mucosubstances secreted by epithelia of various organs, such as the disgestive tract, lungs, and cervix. Glycogen, normally found in many cells, skin, liver, muscle is also demonstrated by the PAS stain. It is important to show an increase in the amount of glycogen present in certain pathologic conditions. Certain types of cancer show an increase in glycogen. There are various methods for the PAS. Most show pink to red basement membrance, fungi, glycogen and mucin. A light green or purple (hematoxylin) counterstain can be used.