Which of the following would most strongly suggest that mounting medium was applied after the slide had dried?

• A. Brown pigment stippling and rare glossy black nuclei
• B. Uniformly pink staining across all structures
• C. Absence of any blue nuclear staining
• D. Excess eosin staining

Answer: (A)

The main idea is that applying mounting medium after the slide has dried creates drying-related artifacts that show up in the final mount. When a section is mounted after it has dried, pigment and stain particles can precipitate or become unevenly distributed, and the mounting medium can trap or refract light in a way that alters how the nuclei look. Specifically, brown pigment stippling represents residual pigment that forms granules on a dried surface, while the nuclei can appear as rare glossy black structures because the late mounting creates a strong refractive interface and overemphasizes any remaining stain, masking the normal blue hematoxylin color.

Other patterns—uniform pink staining, absence of blue nuclear staining, or excessive eosin staining—are more about over- or understaining or staining quality, not about the timing of mounting relative to drying.