Which technique is most likely used for detecting reducing substances in tissues?

• A. Schmorl technique for reducing substances
• B. PAS
• C. Alcian blue pH 2.5
• D. Crystal violet

Answer: (A)

Detecting reducing substances in tissue sections relies on a method that specifically targets sugars capable of donating electrons. The Schmorl technique is that histochemical approach; it’s designed to reveal reducing substances like certain sugars in situ, producing a visible staining pattern where these substances are present.

In contrast, PAS detects carbohydrates in general by oxidizing them to create aldehydes that react with Schiff’s reagent, which highlights a broad range of carbohydrate-containing structures but isn’t limited to reducing substances. Alcian blue at pH 2.5 stains acidic mucopolysaccharides and glycosaminoglycans, not reducing sugars specifically. Crystal violet is a general dye used for staining and differentiation of cells and organisms, not a method for detecting reducing substances in tissues.