Products of platelet degranulation include:

c. Transforming growth factor b

d. Platelet-derived growth factor

The initial response to injury and disruption of a blood vessel is bleeding. The hemostatic response to this is clot formation to stop hemorrhage. Platelet plug formation initiates the hemostatic process along with clotting factors activated by collagen and the basement membrane proteins exposed by the injury. Platelets then degranulate, releasing the contents of their alpha granules and dense granules, most notably platelet derived growth factor and transforming growth factor b. These substances initiate chemotaxis and proliferation of inflammatory cells, beginning the inflammatory response that will ultimately heal the wound. Tumor necrosis factor and interleukin-1 also stimulate fibroblast proliferation, however are produced by macrophages.