Effect of mGPVI on platelet adhesion. Heparinized whole blood from wild-type mice was incubated with the indicated concentration of mouse GPVI-Fc (gray bars) or the same concentration of control IgG (black bar) for 2 minutes and perfused at wall shear rates of 1000 seconds^–1 (4 minutes) over a collagen-coated surface. Surface area covered by thrombi is summarized in the upper panels (mean ± SD of 5 experiments per group). Control bar represents blood from wild-type mice incubated with 30 μg/mL of irrelevant IgG, but similar results were also obtained with higher concentrations (not shown). Lower panels show representative phase-contrast images taken at the end of the experiment. (*P < .05)