The preferred fixative for the technique in the image is

• A. NBF
• B. Formalin
• C. Glutaraldehyde
• D. Ethanol

Answer: (A)

The main idea is that routine histology requires a fixative that preserves tissue structure without introducing artifacts and is compatible with paraffin embedding and standard staining. Neutral buffered formalin does exactly that. Its formaldehyde cross-links proteins to lock in cellular and tissue architecture, while the buffering keeps the solution at a neutral pH. This combination minimizes acid-related artifacts and preserves antigenicity well enough for common stains and many immunohistochemical procedures after antigen retrieval.

Plain or unbuffered formalin can become acidic over time, leading to artifacts and variable staining. Ethanol fixes by dehydration and can cause tissue shrinkage and hardening, distorting morphology and not providing the same excellent overall preservation needed for paraffin sections. Glutaraldehyde provides very strong cross-linking and is superb for electron microscopy, but its intense fixation can mask epitopes and complicate routine paraffin processing and staining, making it less suitable for standard histology workflows.

So, neutral buffered formalin is the preferred fixative because it best balances morphology preservation, compatibility with paraffin processing, and downstream staining quality.