In vivo thrombogenesis in ferric chloride–injured mesenteric arterioles. (A) Time to first thrombus formation. Calcein AM–labeled platelets representing approximately 2.5% of total platelets were observed in mesenteric arterioles of live mice after injury with 10% ferric chloride. The time required for formation of a thrombus more than 30 μm was measured. (B) Occlusion time. The time required for a complete stop of blood flow was measured after injury with 10% ferric chloride. Symbols represent data from a single mouse. Bars represent the mean values of groups (n = 16 for Adamts13^L/L mice, n = 16 for Adamts13^S/S mice, and n = 12 for Adamts13^−/− mice).