The Gridley stain uses which reagents?

• A. Chromic acid and Schiff reagent
• B. Methylene blue and eosin
• C. Silver nitrate and ammonia
• D. Hematoxylin and eosin

Answer: (A)

Gridley stain is a Schiff-type histochemical reaction that detects carbohydrates in tissue. The key step is oxidizing the sugar components with chromic acid, which converts them to aldehyde groups. Schiff reagent then reacts with those aldehydes, giving a magenta color that highlights mucosubstances such as glycogen, mucins, and basement membranes. This requirement for chromic acid as the oxidizing agent and Schiff reagent as the color-generating partner is what makes this stain specific for carbohydrate-containing structures. Other stains use different mechanisms or dye combinations (for example, general dyes like hematoxylin and eosin stain nuclei and cytoplasm without targeting carbohydrates, while silver-based methods or other dye pairs don’t rely on the chromic acid–Schiff chemistry), which is why the chromic acid with Schiff reagent combination is the correct pairing for Gridley stain.