Uptake of biotinylated PCI by platelets. Washed platelets in suspension were incubated with 2 different concentrations of biotinylated PCI for 2 different periods of time, namely, 4.5 μg/mL for 7 minutes (A) and 15 minutes (B) or 9 μg/mL for 7 minutes (C) and 15 minutes (D). Uptake was stopped by addition of fixative and platelets were then processed for transmission electron microscopy. Biotinylated PCI was detected by incubating platelets sections with 10 nm gold-labeled streptavidin. Dose- and time-dependent internalization of biotinylated PCI was observed, which conduced the biotinylated PCI molecules to the  granules (arrowheads). Bars = 200 nm.