Which staining technique is used to identify collagen in tissues?

Masson's trichrome stain is a specific staining technique that highlights collagen in tissues. The method distinguishes collagen fibers from other types of tissue components, making it invaluable in histopathology for the assessment of connective tissue disorders, fibrosis, and tumor stroma.

In a Masson's trichrome stain, collagen appears blue or green, while muscle and cytoplasm typically stain red. This clear differentiation enhances the ability to visualize and assess the distribution and quantity of collagen within tissue samples. Because collagen is a major structural component in tissues, this stain can provide crucial information on pathological changes, such as scarring or fibrosis.

Other staining techniques mentioned do not specifically target collagen or do not provide the same clarity in distinguishing it from surrounding tissue components. Hematoxylin and eosin stain is the most common stain used for overall tissue morphology, but it does not specifically highlight collagen. The Periodic acid-Schiff stain is effective for visualizing carbohydrates and glycoproteins rather than collagen. Giemsa stain is primarily used for blood smears and certain cytological specimens and does not provide detailed visualization of collagen. Thus, Masson's trichrome stain is the best choice for identifying collagen in tissues.