Which fixative is used to fix touch preparations and blood smears?

• A. Acetone
• B. Methyl Alcohol
• C. Ethyl Alcohol
• D. Carnoy's Solution

Answer: (B)

Methanol fixes touch preparations and blood smears quickly by coagulating cellular proteins, which preserves the integrity of both the cytoplasm and nuclei and allows stains like Wright-Giemsa to penetrate evenly. This rapid, protein-precipitating action helps maintain accurate morphology of blood cells and the delicate structures seen in touch impressions, reducing artifacts that could mislead interpretation. Acetone and ethanol are dehydration-type fixatives that can cause more distortion or inconsistent staining in blood smears, while Carnoy's solution is a stronger fixative used for specific cytology procedures and can alter nuclear detail. For routine touch preps and blood smears, methanol is the best option.