Pathological endogenous deposits are part of the pigmented deposits, tissue cells undergo certain pathological changes to form deposits with different shape characteristics, this polymerization forms a special protein that is able to show fibrin protein after staining. Fibrin is a special protein formed by the polymerization of fibrin molecules present in the blood, also known as fibrin, under normal conditions it is a special protein formed by the polymerization of fibrinogen molecules in the blood, this protein exists in the form of curved filamentous fibrin in the tissues, most of them are in the form of reticulation, sometimes in the form of coarse fibrin webs, and the old ones can be agglomerated into amorphous lumps; when the tissues are When the vascular endothelium is more severely damaged, the vascular permeability is increased, which can lead to the leakage of large amounts of fibrin.