Masson's Trichrome Stain - Chemistry

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Masson's Trichrome Stain - Chemistry

Trichrome stains, such as the Masson's Trichrome are named because of the three dyes used in the staining procedure. Using acid-base chemistry, these three dyes are employed to selectively stain muscle, collagen fibers, fibrin, and erythrocytes. Tissue sections are first placed in Bouin’s solution. Bouin’s solution acts as a mordant to link the dye to the targeted tissue components. Nuclei are stained with Weigert’s hematoxylin, an iron hematoxylin, which is resistant to decolorization by the subsequent acidic staining solutions. Biebrich scarlet-acid fuchsin solution stains all acidophilic tissue elements such as cytoplasm, muscle, and collagen. Subsequent application of phosphomolybdic/phosphotungstic acid is used as a decolorizer that causes the Biebrich scarlet-acid fuchsin to diffuse out of the collagen fibers. This leaves the muscle cells stained red. The phosphomolybdic/phosphotungstic acid also serves as a link between the decolorized collagen and aniline blue, which is applied after this differentiation step. Following aniline blue staining, 1% acetic acid is applied to differentiate the tissue sections.

Masson's trichrome stain