Which reagent is the final collagen stain in the Masson Trichrome protocol?

Study for the CAMLPR Histology Practice Test. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

In Masson trichrome, the final color for collagen comes from a dye that is applied after the differentiating step to specifically bind to collagen. This last staining step uses either light green or aniline blue, which colors collagen blue or green depending on the dye chosen. The earlier reagents set up and differentiate the tissue components: Bouin's fixative helps with staining intensity, Weigert's iron hematoxylin stains nuclei, and the phosphomolybdic–phosphotungstic acid differentiator prepares the tissue so collagen will take up the final dye. So the reagent that directly produces the final collagen color is the light green or aniline blue stain.