Epidermal growth factor: has the effect of promoting proliferation of epithelial cells, fibroblasts, etc.; platelet-derived growth factor: derived from platelets, released during the coagulation process, has effects on fibroblasts, smooth muscle cells, etc. Proliferation-promoting effect; fibroblast growth factor: can promote the proliferation of a variety of interstitial cells and small blood vessels; transforming growth factor: can stimulate the proliferation of interstitial cells; many other cytokines such as interleukins, tumor necrosis factor, etc. also have the effect of promoting the growth of interstitial cells and small blood vessels. The functions of fibroblast proliferation and collagen synthesis.