Which of the following is a lipid stain used to visualize lipids?

Which of the following is a lipid stain used to visualize lipids?

• A. Hematoxylin
• B. Oil Red O
• C. Eosin
• D. Crystal violet

Answer: (B)

Staining lipids requires a dye that partitions into lipid-rich areas. Oil Red O is fat-soluble, so it dissolves in neutral lipids like triglycerides and cholesteryl esters, coloring them bright red-orange. This makes lipid droplets visible under light microscopy, especially on frozen sections where lipids are preserved. Hematoxylin targets basophilic structures such as nuclei, and eosin stains eosinophilic cytoplasm; neither is specific for lipids. Crystal violet is used in Gram staining and other histology applications but does not visualize lipids. Because routine paraffin processing removes lipids, lipid staining is typically performed on unfixed or frozen tissue sections. Thus, the lipid stain used to visualize lipids is Oil Red O.

Staining lipids requires a dye that partitions into lipid-rich areas. Oil Red O is fat-soluble, so it dissolves in neutral lipids like triglycerides and cholesteryl esters, coloring them bright red-orange. This makes lipid droplets visible under light microscopy, especially on frozen sections where lipids are preserved. Hematoxylin targets basophilic structures such as nuclei, and eosin stains eosinophilic cytoplasm; neither is specific for lipids. Crystal violet is used in Gram staining and other histology applications but does not visualize lipids. Because routine paraffin processing removes lipids, lipid staining is typically performed on unfixed or frozen tissue sections. Thus, the lipid stain used to visualize lipids is Oil Red O.