Platelet adhesion and thrombus formation in β1-null mice. (A) Flow cytometric analysis of glycoprotein expression on wild-type (black line) and β1-null (shaded area) mice. (B) Platelet-vessel wall interactions after vascular injury were investigated in wild-type (β1 fl/fl) and β1-null mice by in vivo fluorescence microscopy of the common carotid artery in situ. The left and right graphs summarize platelet adhesion and aggregate formation, respectively, of 7 experiments per group. Results are shown as mean ± SEM. (C) The photomicrographs show representative in vivo fluorescence microscopy images 3 minutes after injury in wild-type and β1-null mice. (D) Representative histologic sections of carotid arteries 20 minutes after injury demonstrating large platelet-rich thrombi in wild-type and β1-null mice.