Which stain is used to visualize neutral fats in tissue sections?

• A. Oil Red O
• B. Perl's Prussian Blue
• C. Periodic Acid Schiff's
• D. Hematoxylin

Answer: (A)

To visualize neutral fats in tissue sections, you need a dye that specifically binds lipids. Oil Red O is a fat-soluble dye that stains neutral lipids—such as triglycerides and cholesterol esters—red, making fatty deposits easy to see. Lipids are preserved in frozen (cryo) sections, not in standard paraffin-embedded tissue, because paraffin processing dissolves lipids, so Oil Red O is usually applied to frozen sections. The other stains target different substances: Perl’s Prussian Blue detects iron deposits (blue), Periodic Acid Schiff highlights carbohydrates like glycogen and mucosubstances, and Hematoxylin stains nuclei and basophilic structures. So Oil Red O is the stain of choice for neutral fats.