(A) Time course of platelet thrombus development at wall shear rate of 300 s⁻¹ (top) or 1,500 s⁻¹(middle), obtained using washed blood cells with or without the addition of fibrinogen (Fg) or vWF, either individually or concurrently as indicated. The concentration of fibrinogen was 2 mg/mL, corresponding to the lower limit in normal plasma, but in excess of the amount needed to saturate _IIbβ₃; that of vWF was 20 μg/mL, approximately twofold higher than in normal plasma to compensate for the loss of larger multimers during purification. All results are reported as mean ± SEM of between four and six experiments for the different conditions analyzed. Open triangles in the middle panel indicate the results obtained with washed cells plus vWF in the presence of 100 μg/mL of the anti-_IIbβ₃ monoclonal antibody, LJ-CP8. (B) The results at wall shear rate of 1,500 s⁻¹ shown in (A), but expressed as the mean ± SEM of the rate of change in thrombus volume during successive time intervals.