Which problem describes inconsistent staining due to mounting, involving protein trapping?

• A. Protein evenly distributed.
• B. Protein removed during mounting.
• C. Protein trapped beneath the tissue during mounting process.
• D. Protein not involved.

Answer: (C)

Mounting artifacts in immunohistochemistry can cause inconsistent staining, and one specific problem is protein trapping beneath the tissue during mounting. When the mounting medium and coverslip are applied, proteins can become sealed beneath the tissue surface, making them less accessible to antibodies or causing them to concentrate in localized areas. This leads to patchy or uneven staining across the section. If the protein were simply evenly distributed, staining would be uniform; if it were removed during mounting, you'd expect overall loss of signal rather than localized inconsistency; if the protein weren’t involved, mounting wouldn’t create this staining pattern.