Which reagent is used in both Masson trichrome and van Gieson staining?

• A. Acid fuchsin
• B. Aniline blue
• C. Beibrich scarlet
• D. Chromotrope 2R

Answer: (A)

Masson trichrome and van Gieson share a red dye that stains muscle and cytoplasm. In both methods, acid fuchsin provides that red coloration, helping differentiate these elements from connective tissue. In Masson trichrome, a red component is produced (often with Biebrich scarlet and acid fuchsin) while collagen is stained blue by aniline blue. In van Gieson, acid fuchsin combines with picric acid to give red for muscle and cytoplasm and yellow for collagen. So acid fuchsin is the common reagent that appears in both stains.