Which fixative is associated with the Masson Trichrome protocol?

• A. Bouins
• B. Formalin
• C. Alcohol
• D. Glutaraldehyde

Answer: (A)

Masson trichrome relies on a fixative that preserves tissue while enhancing dye differentiation. Bouin’s fixative, which contains picric acid, formaldehyde, and acetic acid, is traditionally used with this protocol because it helps proteins stay in place and increases contrast so collagen stains blue (or green), muscle and cytoplasm stain red, and nuclei stain dark. The other fixatives don’t provide the same staining balance for this method: formalin isn’t specific to promote the same differential uptake, alcohol can cause more dehydration and less distinct separation, and glutaraldehyde is geared toward ultra-structural preservation rather than the color contrast needed in light microscopy trichrome staining.