Dependency of platelet adhesion to mouse fibrin on plasma VWF. Platelet-surface contacts are depicted as a function of perfusion time for wild-type mouse blood perfused over wild-type mouse fibrin (•), VWF-deficient mouse blood perfused over wild-type mouse fibrin (▴), and wild-type mouse blood perfused over VWF-deficient mouse fibrin (□). Perfusions were performed at a shear rate of 1000 s^–1. Values are mean ± SEM of 3 independent experiments. Error bars indicate SEM.