Overstaining with hematoxylin or metanil yellow will obscure which properties of Mayer mucicarmine staining?

• A. Carminophilic properties
• B. Nuclear detail
• C. Basophilic properties
• D. Tissue architecture

Answer: (A)

The key idea here is that Mayer mucicarmine staining identifies mucin by a carminophilic reaction—the mucin binds carmine and stains red/magenta. If you overdo the counterstain with hematoxylin (blue) or metanil yellow, that red carminophilic signal gets obscured by the heavy counterstain, making the mucin’s carmine staining hard to see. So the property most affected by overstaining is the mucin’s carminophilic staining. Nuclear detail and overall tissue architecture may still be visible, but the specific red color indicating mucin via carmine is masked.