FeCl₃-induced thrombosis in the mesentery. (A) Images of mesenteric venules taken 13 minutes after FeCl₃ injury. Platelets were labeled by infusion of fluorophore-labeled antibodies to platelet receptor GPIX. White bar = 100 μm. Dotted lines mark the vessel wall. Representative of 5 independent experiments. (B) Embolizing thrombi in clopidogrel-treated WT animals stained positive for JON/A-PE, a probe that selectively detects the activated form of αIIbβ3 integrin.²³  Representative of 3 experiments. (C) Mean occlusion time in FeCl₃-injured venules of mice of WT (solid black bar), WT/clopidogrel (WT + clop., solid white), and CalDAG-GEFI^−/− (KO, checkered) mice (n = 7-9). Note that none of the WT/clopidogrel or CalDAG-GEFI^−/− mice occluded within the 40 minutes observation period. (D) Average time required to form a first thrombus of more than 20 μm in diameter. (E) Number of emboli with a diameter of more than 20 μm forming 8-13 minutes after FeCl₃ injury. Mean venule diameter: WT: 254.9 ± 19.5 μm; WT + clopidogrel: 305 ± 28.7 μm; CalDAG-GEFI^−/−: 239 ± 13.7 μm; P = NS for all comparisons. All images were obtained on a Nikon Eclipse Ti-U inverted microscope (Nikon) equipped with a Retiga EXL monochrome camera (QImaging) and the Nikon NIS Elements software (NIS-Elements Advanced Research).