Detection of abciximab by immunogold labeling using an affinity-purified rabbit antibody specific for c7E3. Examined were frozen ultrathin sections of platelets taken from patient 1 (A) 3 hours or 19 hours (B through E) into the infusion. High-power magnifications of a labeled -granule and of thin tortuous channels of the SCCS are shown in (C) and (E), respectively. In (D) a very thin aperture in the membrane of -granule at a point of junction of a thin channel is shown and indicated between two arrows. Bars = 0.2 μm.