The pathological endogenous precipitate is a part of pigment precipitate. After certain pathological changes， the tissue cells form the precipitate in different shapes and characteristics. This special protein polymer can show cellulose protein after dyeing. Cellulose is a special protein formed by the aggregation of fibrin molecules in the blood， also known as fibrin. Under normal circumstances， this kind of protein exists in the tissue in the form of curved filamentous cellulose， most of which are in the form of network structure， sometimes in the form of thick cellulose network， and old agglutinable in the form of amorphous block. When the tissue is damaged， the vascular endothelium is seriously damaged， and the vascular permeability increases accordingly， which can lead to the leakage of a large number of fibrin.

The Fibrin Stain Kit (Upgraded MSB Method) has been optimized and upgraded based on DR0411， still using Matthew yellow-acid red-aniline blue as the core， mainly composed of Celestite Blue Solution， Mayer Hematoxylin Solution， Mathew Yellow Solution and Aniline Blue Solution. The differences are that the Acid Red Solution has been improved and adjusting the concentration of the Weak Acid Solution to 3×. This product is a simple and inexpensive cellulose staining kit. After staining， conventional cellulose is red， old cellulose is blue， red blood cells are yellow， and collagen fibers are blue or blue purple.