Immunogold labeling for abciximab on ultrathin sections of platelets taken (A) 20 hours after the end of the abciximab infusion (patient 1), (B) 15 hours after the end of the infusion (patient 3), (C) 67 hours after the end of the infusion (patient 1), (D) 1 week after the end of the infusion (patient 3). There is a notable decrease in the labeling at the longer time points. Bars = 0.2 μm.