Connective tissue is narrowly defined as the three types of fibers it contains: collagen fibers, reticular fibers, and elastic fibers, and collagen fibers (collagen fibers) are the more widely distributed and abundant type of fibers.Masson trichrome staining, also known as Masson staining, is one of the classic methods of staining connective tissues, and it is the authoritative and classic technical method of staining collagen fibers.The so-called trichrome staining usually The so-called trichrome staining usually refers to the staining of the nucleus and can selectively display collagen fibers and muscle fibers, the staining principle of this method is related to the size of the anionic dye molecule and the penetration of the tissue: the size of the molecule is reflected by the molecular weight, small molecular weight is easy to penetrate into the tissue of dense structure and low penetration, while the large molecular weight can only enter into the structure of loose tissue with high penetration; Pollak Trichrome Staining is on the basis of the Masson Trichrome Staining method. Pollak trichrome staining is a multicolor staining method of connective tissue improved on Masson trichrome staining method, which adopts mordant and dye-promoting agent to dye at the same time, and it can make multiple components in connective tissue color.

The biggest feature of Pollak trichrome staining is that the core dyes of Masson trichrome staining are fused together, which greatly simplifies the operation steps, in addition to its features: ① stable staining; ② short differentiation time, 1-2s; ③ suitable for paraffin sections; ④ the stained sections are preserved for a long time and are not easy to fade.