Which description matches Zamboni's solution?

• A. Paraformaldehyde, Picric Acid, DI Water, Phosphate buffer, NaOH to pH 7.3
• B. Formaldehyde-based fixative with alcohol
• C. Glyoxal-based fixative with phosphate buffer
• D. Acetone-based fixative

Answer: (A)

Zamboni's solution is a neutral buffered fixative that combines paraformaldehyde with picric acid in an aqueous, phosphate-buffered environment, with the pH adjusted to about 7.3 using NaOH. The paraformaldehyde provides cross-linking of proteins, helping preserve tissue architecture, while picric acid acts as a coagulative fixative that enhances contrast and preserves cytoplasmic detail. The buffer maintains a near-neutral pH, which helps minimize excessive hardening and shrinkage that can occur with more acidic fixatives, and the pH adjustment with NaOH ensures stability around 7.3.

This is distinct from fixatives that are primarily alcohol-based or acetone-based, or from glyoxal-based formulations, which is why the description with paraformaldehyde, picric acid, water, phosphate buffer, and a pH-adjusting agent to ~7.3 best fits Zamboni's solution.