In vivo thrombus formation. (A) Representative images of FeCl₃-injured mesenteric venules in WT and PN-1–deficient mice. Thrombus formation was visualized in real time using an inverted epifluorescent microscope (Nikon Eclipse TE 2000-U) using a lens at 20×/0.5 (Nikon). Images were acquired using a CCD CoolSNAP HQ² camera (Photometrics/Roper Scientific) and processed with Metamorph 7.0r1 software (Universal Imaging Corporation). (B) Time to occlusion of mesenteric venules (black histograms) and arterioles (gray histograms) was measured after application of FeCl₃ in WT mice and PN-1^−/− mice. Data are the mean ± SD for the number of mice indicated in parentheses. ***Significant difference (P < .001) versus WT.