Embolization of Tsp1^-/- platelet thrombi. (A) Examples of thrombus formation and sudden embolization (as indicated by the time in seconds) of large thrombi after intestinal venule damage in Tsp1-null mice. Scale bars represent 50 μm. (B) Mean number (± SEM) of embolization cycli before occurrence of occlusion in venules and arterioles of WT and Tsp1-null mice for the number of vessels indicated (v). P values were calculated via nonparametric Mann-Whitney test, with 2-tailed P value (^*P < .001 between mean number of embolizations in WT and TSP-1-null mice).