In the Periodic Acid-Schiff (PAS) stain, iodine is used in the form of Schiff's reagent. The PAS stain is utilized to detect polysaccharides such as glycogen, mucosubstances, and glycoproteins in tissues. Periodic acid oxidizes the polysaccharides, creating aldehyde groups that react with Schiff's reagent to produce a magenta color. This color change allows for the visualization of polysaccharide-rich structures in tissue samples.
