Effect of incorporation of plasma fibronectin on platelet thrombus formation on collagen or VWF under shear conditions. (A) A suspension of platelets and red blood cells was mixed with or without 50 μg/mL FITC-fibronectin (FITC-FN) and perfused over surfaces coated with collagen (CL) or VWF at a wall shear rate of 1250 s^–1 or 5000 s^–1 for 5 minutes without LPA. Coverslips were taken out of the chamber and processed for epifluorescence microscopy. The small and large pictures were taken with 10 × (bar = 100 μm) and 100 × (bar = 10 μm) objectives, respectively. (B) FUD, 1 μM, was coperfused with FITC-FN. The images of phalloidin-stained platelets should be compared with images on collagen of panel A. (C) After perfusion, nonpermeabilized platelets were incubated with mouse anti–human fibrinogen (FG) followed by rhodamine-conjugated anti–mouse IgG antibody. Confocal microscopy of FITC-fibronectin and secreted fibrinogen was performed as described in “Materials and methods.” The images represent a 1-μm slice taken from 4-μm height of the coverslip. The right panel shows a perpendicular section through the line. Bar = 10 μm.