Which statement about zinc formalin as a substitute for B5 is most accurate?

• A. Zinc formalin is a substitute for B5
• B. Zinc formalin is a non-additive fixative
• C. Zinc formalin is obsolete in histology
• D. Zinc formalin prevents nuclear detail

Answer: (A)

Zinc formalin can replace B5 because it provides similar tissue preservation while offering practical advantages. The zinc salt in the fixative supports protein cross-linking and stabilization, which yields good tissue architecture and especially solid nuclear detail, a key goal when using fixatives like B5. It also avoids the hazards associated with picric acid in Bouin’s/B5, making it a safer alternative in many lab settings. Because of these qualities, zinc formalin is still used as a substitute rather than being considered obsolete.

The other statements aren’t accurate. It isn’t described as a non-additive fixative; it’s used precisely for its additive fixation effects with zinc. It’s not obsolete in modern histology, and it does not prevent nuclear detail; it tends to preserve nuclear features well, contributing to clear hematoxylin–eosin staining profiles.