What is the primary effect of adding acetic acid to the hematoxylin solution?

• A. Increases nuclear selectivity
• B. Increases cytoplasmic staining
• C. Stains lipids
• D. Reduces staining intensity

Answer: (A)

The main effect being tested is how the hematoxylin staining becomes more selective for nuclei when acetic acid is added. Acetic acid lowers the solution’s pH, which enhances the affinity of the hematoxylin-mordant complex for nuclear material (the nucleic acids) and reduces non-specific binding to cytoplasmic components. This results in more intense, crisp nuclear staining while keeping the cytoplasm relatively less stained, improving overall nuclear detail.

So the correct choice reflects that adding acetic acid increases nuclear selectivity. It does not stain lipids, it does not reduce staining intensity, and it does not specifically increase cytoplasmic staining.