Fixative for Alcian blue PAS hematoxylin?

• A. 10% NBF
• B. Zenker solution
• C. Bouin's fixative
• D. Carnoy's solution

Answer: (A)

Alcian blue–PAS–hematoxylin staining relies on preserving mucins and carbohydrate-rich structures without chemically altering or removing them. A fixative that gently cross-links proteins without harsh dehydration or additions that interfere with the dyes is key. Neutral buffered formalin preserves both acidic and neutral mucins well and maintains the integrity of carbohydrate groups needed for the PAS reaction. It provides reliable, stable staining and avoids introducing fixative components that can mask mucin content or create background artifacts.

In contrast, fixatives like Zenker’s (mercuric-based), Bouin’s (picric acid-containing), and Carnoy’s (alcohols with acetic acid) can alter or extract mucopolysaccharides and carbohydrates, cause background staining or pigment issues, and generally produce less consistent AB staining. Therefore, 10% neutral buffered formalin is the best choice for Alcian blue PAS hematoxylin.