Which solvent is not a component of Carnoy fluid?

• A. Glycerol
• B. Chloroform
• C. Acetic acid
• D. Alcohol

Answer: (A)

Carnoy's fixative is a rapid-acting cytology fixative made from a mix of alcohol (ethanol), chloroform, and acetic acid. Each component has a specific role: alcohol acts as a dehydrating fixative that precipitates proteins; chloroform helps dissolve lipids and improves penetration and clearing; acetic acid rapidly fixes nucleoproteins and helps preserve nuclear detail, though it can cause some swelling if used alone. Glycerol, on the other hand, is a viscous, hygroscopic polyol. If included, it would slow penetration, interfere with dehydration and clearing, and alter fixation quality, which is undesirable for the precise preservation needed in Carnoy’s fluid. Therefore, glycerol is not a component of Carnoy fluid.