In the Bakers acid hematein method, differentiation is accomplished by which reagent?

• A. Borax ferricyanide
• B. Sodium carbonate
• C. Ammonium hydroxide
• D. Acetic acid

Answer: (A)

In this staining approach, differentiation is the step that fine-tunes which hematoxylin complexes stay bound in the nuclei and which are removed to reduce background. The reagent used is borax ferricyanide. The ferricyanide component acts as a mild oxidizing differentiator that helps convert weakly bound hematoxylin to a form that is more readily dissolved away, while the nucleus-bound hematoxylin–mordant complex remains intact. The borax buffers the solution to keep the pH stable, so differentiation is selective rather than aggressive. This combination gives crisp, deep nuclear staining with minimal nonspecific background. Other differentiators that simply raise or lower pH without this controlled oxidative action don’t achieve the same selective removal, so they’re not used in this method.