H&E stained slides show hazy blue nuclei, but recuts from the tissue processed a week previously and stained in the same basket show excellent nuclear staining. One possible cause is:

• A. The use of too much heat during processing
• B. Inadequate differentiation
• C. Over-differentiation of hematoxylin
• D. Insufficient dehydration

Answer: (A)

Excess heating during tissue processing can directly affect how nuclei take up hematoxylin and how crisp that staining appears. When the processing workflow uses too much heat, tissue proteins can denature more than intended and the hematoxylin–hematoxylin complexes can be altered, reducing nuclear contrast. The nuclei end up staining blue but with blurry, hazy edges rather than sharp detail. In contrast, recuts from the same tissue block processed earlier (with different heat exposure) show strong, well-defined nuclear staining because the fixation and dye uptake were more appropriate. So, overheating during processing is a plausible cause of the hazy nuclei seen in the current slides.