Collagen exposure after injury at varying FeCl₃ concentrations and effect of lepirudin on thrombus formation in wild-type mice. (A) Injuries in wild-type mice (WT) were induced by application of 10% or 8% FeCl₃ for 5 or 2 minutes, respectively. Collagen exposed to the blood circulation was labeled by injection of a rabbit anti–mouse collagen type I antibody (1 μg/g body weight) plus Alexa 488–conjugated goat antirabbit antibody (1μg/g body weight). Integrated fluorescence intensity of collagen at several time points after injury is indicated for individual thrombi under the 2 conditions (n = 5 for each condition). (B) Local administration of an 8% solution of FeCl₃ for 2 minutes to the adventitial surface of the mesentery was used to induce vascular injury in wild-type mice. Mice were treated with 5 μg/g body weight of lepirudin prior to vessel injury where indicated. For each thrombus the time to the formation of an initial thrombus is reported and the median time indicated (n = 10). (C) For each thrombus in panel B the time to vessel occlusion is reported. Most vessels did not occlude during the 30 minutes of the experiment.