Which fixative contains 95% alcohol, acetic acid, formaldehyde, and picric acid?

• A. Gendre
• B. Bouin
• C. Carnoy
• D. Helly

Answer: (A)

The fixative described is best identified by its combination of components: a high-percentage alcohol, acetic acid, formaldehyde, and picric acid. This four-part mixture is characteristic of Gendre’s fixative. The strong alcohol component provides rapid penetration and dehydration, while acetic acid helps preserve nuclear detail and swells cytoplasmic elements. Formaldehyde cross-links proteins to lock cellular structures in place, and picric acid further fixes proteins and enhances staining contrast. Among common fixatives, Bouin’s uses picric acid with formaldehyde and acetic acid but not a high-alcohol component; Carnoy’s uses alcohol and acetic acid (and sometimes chloroform) but not formaldehyde or picric acid; Helly’s involves formaldehyde with alcohol and acetic acid but typically not picric acid. So the described composition points to Gendre’s fixative.