In vitro thrombogenesis on collagen surface under flow. (A) Thrombus formation at 1000 s⁻¹. Whole blood from Adamts13^L/L, Adamts13^S/S, or Adamts13^−/− mice containing mepacrine-labeled platelets was perfused over an acid-insoluble type I collagen–coated surface at a wall shear rate of 1000 s⁻¹. The cumulative thrombus volume, analyzed using a multidimensional imaging system, was measured every 0.5 minutes until 4 minutes. Data are the mean ± SEM of 25 mice for each genotype. (B) Thrombus formation at 5000 s⁻¹. Whole-blood samples from indicated mice were perfused over an acid-insoluble type I collagen–coated surface at a wall shear rate of 5000 s⁻¹. The cumulative thrombus volume was measured every 20 seconds until 80 seconds. Blood from 2 mice was pooled and used for experiments. Data are the mean ± SEM of 15 samples for each genotype. *P < .05 in comparison with Adamts13^L/L mice.