Schiff reagent is described as what form?

• A. A reduced solution of basic fuchsin
• B. A solution of eosin
• C. A solution of hematoxylin
• D. A solution of Cresyl violet

Answer: (A)

Schiff reagent is described as a reduced solution of basic fuchsin. It’s made by treating basic fuchsin with sulfurous acid, which decolorizes the dye to a colorless form. In the periodic acid–Schiff reaction, periodic acid oxidizes tissue carbohydrates to aldehydes, and those aldehyde groups react with the Schiff reagent to restore the magenta color. This color development highlights glycogen and other carbohydrate-rich structures in the tissue. The other dyes listed (eosin, hematoxylin, Cresyl violet) are different staining reagents and do not describe the Schiff reagent itself.