Periodic acid-Schiff stain (PAS)

General: Stains polysaccharides (including glycogen). Often used to stain glomeruli in kidney tissue and to demonstrate glycogen in the liver. Fungi with carbohydrate capsules stain PAS positive. Very versatile and can be used for a variety of other tissue components such as mucin, hyaluronic acid, reticulin, fibrin of thrombi, colloid droplets, hyaline of arteriosclerosis, granular cells in renal arterioles where preserved, most basement membranes, colloid of pituitary stalks and thyroid. All positive PAS components stain rose to purplish red/magenta.

Standard/common uses: Usually non-tumor, but has a wide variety of applications. Can be used in conjunction with a pre-rinse in diastase, which specifically removes glycogen. In very rare institutions, it reportedly has been used as a standard stain over H and E.

• Infectious: (parasites, adequate fungal stain but not ideal - suggest GMS)
• Liver: glycogen, reticulin
• Kidney: glomeruli, reticulin, granular cells of renal arterioles, basement membranes

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