Which stain is commonly used to stain collagen?

• A. Van Gieson
• B. Oil Red O
• C. Aldehyde fuchsin
• D. Masson trichrome

Answer: (A)

Staining collagen requires a dye system that highlights the collagen fibers while providing contrast with surrounding tissue. Van Gieson uses a mix of picric acid and acid fuchsin. The acid fuchsin component binds to collagen, giving it a pink to red color, whereas the picric acid background colors muscle and cytoplasm yellow. This clear contrast makes collagen fibers easy to identify in connective tissue sections, which is why Van Gieson is commonly used for staining collagen.

For comparison, Oil Red O targets lipids in frozen sections, aldehyde fuchsin highlights elastic fibers, and Masson trichrome also stains collagen but typically yields a blue or green color, depending on the protocol, which is a different visual cue than the pink/red collagen seen with Van Gieson.