Factor IX when activated activates factor X which helps fibrinogen to fibrin conversion. Effects of actin filaments of fibrin clot structure and lysis. It can bind to thrombin that decreases the fibrin formation. XIIIa is an enzyme of the blood coagulation system that crosslinks fibrin. Blood clots that remain in the bladder are digested by urinary urokinase producing fibrin fragments. Plasmin is a serine protease that acts to dissolve fibrin blood clots. The fibrinolytic system then functions to break down fibrinogen and fibrin. Platelets end up being removed and the resulting fibrin strand formation remains. The coagulation cascade of secondary hemostasis has two initial pathways which lead to "fibrin" formation. The covalent bonds increase the stability of the fibrin clot. It reflects the absolute strength of the fibrin and platelet clot. Plasmin proteolytically cleaves fibrin into fibrin degradation products that inhibit excessive fibrin formation. PRF is available as a fibrin clot. This consists of fibrin strands and leukocytes. Ineffective generation or premature lysis of fibrin increases the likelihood of a hemorrhage.