Gαq–/– platelets fail to support thrombus formation in vivo. Carotid vessels of wild-type and Gαq–/– mice were injured by the application of 20% FeCl3 and thrombus formation analyzed by real-time intravital videomicroscopy (data not shown), histologic analysis (A), and scanning electron microscopy (B) 30 minutes after the initial challenge. Light microscopy of hematoxylin/eosin-stained sections revealed well-developed, occlusive thrombi within the carotids collected from wild-type mice, whereas vessels from Gαq–/– mice were effectively clear (representative views in panel A). Original magnification × 2. Electron micrographs of carotid arteries cut longitudinally to view the luminal contents (representative views in panel B) revealed densely packed thrombi in wild-type mice. In contrast, no occlusive thrombi were observed in the lumen of vessels from Gαq–/– mice. Rather, only trace amounts of fibrin-trapped platelets and red cells were observed (inset). Original magnifications × 100 and × 2000 (inset).
