Aniline blue is used in which staining procedures?

• A. Gomori trichrome, Masson trichrome
• B. Masson trichrome only
• C. Verhoeff
• D. Aldehyde fuchsin

Answer: (A)

Aniline blue is used to visualize collagen in connective tissue, providing a blue (or blue-green) contrast that helps differentiate tissue components in trichrome stains. In Masson trichrome, collagen is stained blue by aniline blue, making it easy to distinguish connective tissue from muscle and cytoplasm. Gomori trichrome also highlights collagen with a dye component that yields a contrasting color for connective tissue, so collagen stands out alongside other tissue elements. Stains like Verhoeff and aldehyde fuchsin target elastin rather than collagen and use different dyes, so they do not rely on aniline blue.