1. Oxidation: Tissue sections are treated with periodic acid, which oxidizes the vicinal diols in carbohydrates to form aldehyde groups. 2. Schiff Reagent Application: The tissue is then exposed to Schiff reagent, which reacts with the aldehyde groups to form a magenta compound. 3. Counterstaining: Often, a hematoxylin counterstain is applied to provide contrast and to better visualize cell nuclei.