Which reagent is used as the differentiator in the Bakers acid hematoxylin method?

• A. Borax ferrocyanide
• B. Sodium chloride
• C. Silver nitrate
• D. Aluminum sulfate

Answer: (A)

Differentiation is the step that sharpens nuclear detail by removing excess hematoxylin after staining. In Baker's acid hematoxylin, the differentiating solution is borax ferrocyanide. This combination is chosen because it provides a controlled, mild differentiation that removes non-specifically bound stain while keeping the true nuclear stain intact, yielding crisp blue-black nuclei with minimal background. The other reagents don’t serve this differentiating purpose in this method: sodium chloride adjusts osmolarity, aluminum sulfate acts primarily as a mordant to help stain uptake, and silver nitrate is used for silver-staining procedures, not as a differentiator in Baker’s method.