Characteristics of FVa and FVIII distribution on the surface of activated platelets. Platelets (5 × 10⁴ μL⁻¹) were activated with 100 nM thrombin plus 20 μg/mL CRP (for FVa; we did not add thrombin in case of FVIII), incubated for 5 minutes with specific antibodies to detect FV/FVa and imaged with confocal microscopy. (A) Representative confocal images of DIC, and FITC (green) fluorescence of FV/FVa and FVIII/FVIIIa, and overlay are shown. Scale bars, 5 μm. (B-C) Integral fluorescence for the bound factors. Mean ± SD in (B-C) were determined for 30 to 70 procoagulant platelets analyzed in each experiment.