FeCl₃-induced injury of mesenteric arterioles in control mice and mice with reduced platelet count. Mesenteric arterioles were injured by topical application of 20% FeCl₃, and adhesion and thrombus formation of fluorescently labeled platelets were monitored by in vivo microscopy. Statistical evaluations of (A) time to appearance of first thrombi >10 µm and (B) time to occlusion are shown. The horizontal line indicates the mean value to vessel occlusion. Each symbol represents 1 arteriole (n.s., not significant; *P < .05; **P < .01; ***P < .001). (C-F) Representative images of control and platelet-depleted mice at different time points are depicted. Asterisk indicates stable occlusion of the vessel.