Stock Photo: BLOOD COAGULATION. BLOOD COAGULATION Representation of the platelet aggregation platelets represented in green intervening in the process of coagulation. Under the action of the thrombin, the fibrogens are transfomed into en fibrins and reinforce the meshing created by the platelet aggregation. Formation of a thrombus or clot. see. image 0357407 for the beginning of the process.