Carnoy fluid is prepared with acetic acid, alcohol, and which solvent?

• A. Chloroform
• B. Formalin
• C. Acetone
• D. Glycerol

Answer: (A)

Carnoy's fluid is a rapid fixative that uses acetic acid, an alcohol, and a lipid-solvent to enhance penetration and nuclear detail. The third solvent in this mix is chloroform. Acetic acid helps preserve nucleoproteins and produce good nuclear detail by swelling them; the alcohol fixes and dehydrates the tissue by precipitating proteins; chloroform dissolves lipids and improves penetration, aiding rapid fixation and clearer nuclear morphology. The other options—formalin, acetone, and glycerol—do not make up this fixative: formalin is an aqueous formaldehyde fixative used for routine histology, acetone is another dehydrating solvent but not paired with acetic acid in Carnoy's solution, and glycerol is a humectant rather than the solvent component used here.