In a typical light-microscope preparation stained with hematoxylin and eosin (H&E), which color will the nucleus most often appear?

• A. Colorless/transparent
• B. Blue to purple
• C. Green
• D. Pink to red

Answer: (B)

Verified step by step guidance

1. Understand the purpose of hematoxylin and eosin (H&E) staining: Hematoxylin stains acidic structures, such as nucleic acids in the nucleus, while eosin stains basic components, like proteins in the cytoplasm.
2. Recall that hematoxylin binds to negatively charged molecules (like DNA and RNA) in the nucleus, resulting in a blue to purple coloration.
3. Recognize that eosin stains the cytoplasm and extracellular matrix pink to red, which contrasts with the nuclear staining.
4. Conclude that because the nucleus contains DNA and RNA, it will most often appear blue to purple in an H&E stained preparation.
5. Therefore, the nucleus is not colorless, green, or pink to red, but typically blue to purple due to hematoxylin binding.