Bouin's solution is used as a mordant to intensify color reactions in which stain?

• A. Gomori's One-Step Trichrome Stain
• B. Van Geison's Picric Acid-Acid Fuchsin Stain
• C. Verhoeff's Elastic Stain
• D. Mallory's Phosphotungstic Acid-Hematoxylin

Answer: (A)

Bouin's solution acts as a mordant that boosts dye uptake and color differentiation in certain trichrome procedures. In Gomori's One-Step Trichrome Stain, Bouin's fixative is used to intensify the staining reactions, producing a clear, distinct contrast among tissue elements (for example, collagen highlighting with blue/green tones, muscle or cytoplasm staining red, and nuclei appearing darker). This mordant effect is specific to this trichrome method, which is why this stain is the best choice. Other stains use different mordants or mechanisms—for instance, Verhoeff's elastic stain relies on iron hematoxylin, Mallory's method uses phosphotungstic acid as part of its differentiating system, and Van Geison's stain employs picric acid-acid fuchsin for other tissue components.