Using which nuclear stain can cause mucin to appear bluish in Mayer mucicarmine staining?

• A. Gill hematoxylin
• B. Harris hematoxylin
• C. Mayer's hematoxylin
• D. Ehrlich's hematoxylin

Answer: (A)

In Mayer mucicarmine, mucin is stained red by the mucicarmine dye, while the nuclei are counterstained blue. The shade of blue seen in the nuclei depends on which hematoxylin is used, and Gill hematoxylin provides a very strong, vivid blue counterstain. This intense blue background can make the overall appearance of mucin-containing areas look bluish in some sections, especially when viewed against the deep blue nuclei. So, using Gill hematoxylin is the setup that can cause mucin to appear bluish in Mayer mucicarmine staining. The other hematoxylins tend to produce less intense blue counterstaining, making the bluish shift less likely.