Which statement best explains the observation of very dark nuclei and blue cytoplasm in liver tissue?

• A. Inadequate differentiation of hematoxylin
• B. Over differentiation of eosin
• C. Excess eosin
• D. Incomplete dehydration

Answer: (A)

This pattern comes from under-differentiation of hematoxylin. Hematoxylin stains nuclei blue/purple, and a differentiation step with acid alcohol removes excess stain to prevent overly dark nuclei and to let eosin give the cytoplasm its pink color. If differentiation is inadequate, too much hematoxylin remains, making nuclei very dark and often imparting a blue cast to the cytoplasm as well, because the stain hasn’t been properly controlled. If the issue were over-differentiation of hematoxylin, nuclei would appear lighter; over-differentiation of eosin would dull the pink cytoplasm; incomplete dehydration would cause other artifacts not specifically this blue-nuclei/blue-cytoplasm pattern.