In Bakers acid hematoxylin method, which reagent differentiates?

• A. Borax ferrocyanide
• B. Sodium chloride
• C. Silver nitrate
• D. Potassium permanganate

Answer: (A)

In Baker's acid hematoxylin, differentiation is the step that sharpens the nuclear stain by removing excess color from non-nuclear elements. The differentiating reagent used here is borax ferricyanide. Its action selectively bleaches or oxidizes weaker hematoxylin attachments in the cytoplasm and surrounding tissue while preserving the strong nuclear hematoxylin complex, especially when properly buffered by borax. This gives crisp, blue-black nuclei with minimal background.

Other reagents listed don’t serve this specific role in this protocol: sodium chloride isn’t a differentiator in this method, silver nitrate is used for silver staining procedures, and potassium permanganate is not the differentiator for Baker’s acid hematoxylin.