Which staining solution is used to stain fats in tissues?

Which staining solution is used to stain fats in tissues?

• A. New methylene blue
• B. Giemsa
• C. Eosin
• D. Sudan III or IV

Answer: (D)

Staining fats requires a dye that can dissolve in lipids, so the dye itself must be lipophilic. Sudan III and Sudan IV are fat-soluble, nonpolar dyes that partition into neutral lipid droplets in tissues. When they bind to these fats, the droplets pick up a bright orange-red color, making lipid-rich areas visible under the microscope. The other stains shown are general cytoplasmic or nuclear stains: New methylene blue is a basic dye that highlights nuclei and basophilic structures; Giemsa is used primarily for blood smears and some tissue elements but not specifically for fats; Eosin is an acidic dye that stains cytoplasm and extracellular components pink. None of these selectively stain fats like Sudan dyes do.

Staining fats requires a dye that can dissolve in lipids, so the dye itself must be lipophilic. Sudan III and Sudan IV are fat-soluble, nonpolar dyes that partition into neutral lipid droplets in tissues. When they bind to these fats, the droplets pick up a bright orange-red color, making lipid-rich areas visible under the microscope.

The other stains shown are general cytoplasmic or nuclear stains: New methylene blue is a basic dye that highlights nuclei and basophilic structures; Giemsa is used primarily for blood smears and some tissue elements but not specifically for fats; Eosin is an acidic dye that stains cytoplasm and extracellular components pink. None of these selectively stain fats like Sudan dyes do.