Series of electron micrographs showing platelets in suspension (A and B) and adhered platelets to collagen type III (C and D). Whole blood anticoagulated with Orgaran in the presence of dRGDW was stimulated with 15 μmol/L TRAP (B and D) or vehicle (A and C) at 37°C. After 5 minutes, blood samples were drawn, immediately fixed, and used for immunoelectron microscopy (A and B), and perfusions were started for 5 minutes at a shear rate of 1,600 s^-1 over coverslips coated with collagen type III. Perfused coverslips were also immediately fixed and used for immunoelectron microscopy (C and D). Immunolabeling was performed on frozen thin sections with MoAb AK3 and 10 nm protein-A gold. Closed stars represent the OCS with gold particles. Open star represents OCS without gold particles. Col, collagen. Bar, 200 nm.