Connective tissue is narrowly defined as the three types of fibers it contains: collagen fibers, reticular fibers, and elastic fibers, and collagen fibers are the most widely distributed and abundant type of fibers.Masson trichrome staining, also known as Masson staining, is the most classic method of connective tissue staining, and it is the authoritative and classic technical method of staining collagen fibers. The so-called trichrome staining usually refers to the staining of the nucleus and can selectively display collagen fibers and myofibers, the staining principle of this method is related to the size of the anionic dye molecule and the permeability of the tissue: the size of the molecule is reflected by the molecular weight, small molecular weight is easy to penetrate into the structure of the dense tissue, low permeability; and large molecular weight can only be entered into the structure of the lax tissue with high permeability; however, the molecular weight of the light green or aniline blue is very large, therefore, after Masson staining, myofibers will be stained with the dye. Therefore, after Masson staining, myofibers appear red, and collagen fibers appear green (light green) or blue (aniline blue), which is mainly used to distinguish collagen fibers from myofibers.

The difference between modified Masson trichrome staining and conventional Masson trichrome staining is the use of azurite blue hematoxylin staining of cell nuclei, which is characterized by a short differentiation time (1-2min); clear and bright color; wide range of applicability, suitable for staining of tissue paraffin sections, frozen sections, etc.; the stained sections are preserved for a long time and are not easy to fade; collagen fibers are blue, myofibrils, cytoplasm, cellulose, Collagen fibers are blue, myofibrils, cytoplasm, fibrin, keratin and erythrocytes are red, and nuclei are blue-brown, mainly used to distinguish between collagen fibers and myofibrils.