Which component is not demonstrated by Hematoxylin and Eosin staining?

• A. Lipid
• B. Nuclei
• C. Cytoplasm
• D. RBCs

Answer: (A)

Hematoxylin and eosin staining distinguishes structures based on their chemical affinity for the two dyes: hematoxylin binds basophilic components like nucleic acids in the nucleus, turning them blue/purple, while eosin stains eosinophilic components such as cytoplasmic proteins, giving a pink to red color. Red blood cells also take on the pink color from eosin, so they’re clearly seen in tissues. Lipids, however, are not preserved or stained in routine paraffin-embedded sections because the dehydration and clearing steps dissolve them away. To visualize lipids, special approaches are required, such as frozen sections with lipid-specific stains (like Oil Red O or Sudan stains) or fixation methods that preserve lipids. So the component not demonstrated by standard H&E is lipid.