Mallory's trichrome stain is a reference method for the visualization of connective tissue on histological sections; particularly indicated for the detection of collagen, reticle, cartilage, bone and amyloid.

Mallory's trichrome is based on nuclear staining with carbolfuchsin and associated cytoplasmic staining with G-orange and highly elective collagen staining with aniline blue.

The electivity of the method is based on the different degrees of chemical affinity of the dyes used for tissue macromolecules. The role of phosphomolybdic acid, in particular, is fundamental because it serves as a bridge between the tissue structures to which it selectively binds (collagen fibrils, cell membranes, etc.) and aniline blue (amphoteric dye). The other component of Mallory's trichrome, the orange G, with no affinity for phosphomolybdic acid, stains the remaining structures (which have no link with phosphomolybdic acid).

Here are some examples of Mallory trichrome stains: