In Masson's Trichrome, staining nuclei is accomplished with which reagent?

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

Answer: (A)

In Masson’s Trichrome, the nuclei are given a sharp blue-black color by using aluminum hematoxylin as the nuclear stain. The aluminum mordant creates a stable, crisp nuclear coloring that withstands the subsequent color reactions of the cytoplasmic and connective tissue stains, helping the nuclei stand out clearly against the pink/red cytoplasm and blue collagen. Other hematoxylins like Harris, Ehrlich’s, or Mayer’s are different formulations that can fade or interact less optimally with the trichrome dyes, leading to less defined nuclei or color mismatches in the final stain.