Which function does acid alcohol have in differentiation steps?

• A. Differentiation
• B. Mordant
• C. Reduction
• D. Oxidation

Answer: (A)

Acid alcohol acts as a differentiating agent in staining steps. After the dye has been applied and fixed, acid alcohol selectively removes dye from areas that are not strongly bound, sharpening the contrast so that target structures stand out more clearly. In practice, it decolorizes loosely stained components while leaving the intensely stained targets intact, which is the essence of differentiation. It isn’t a mordant, which is the substance that helps the dye adhere by forming a fixed complex with the tissue; nor is it a reducing or oxidizing agent, which would alter the dye’s chemical state rather than selectively removing excess stain. So its role is differentiation.