Adhesion of RBCs to the endothelial surface following FeCl₃ application. The images in (A-D, upper panels) show the mesenteric venule with visualization by brightfield intravital microscopy (original magnification ×100). The time course was between 1 and 5 minutes after FeCl₃ application. The images in (A-D, lower panels), show the carotid artery with visualization by SEM. The time course was 1 minute for (A-C) and 90 seconds for (D) after FeCl₃ application. Note that for intravital microscopy, the angle of observation is from “below,” looking up the “underside” of the structures, while the angle of observation for SEM is from “above,” looking down at the “top” of the structures. The images in (E-I) show that the adhesion of RBCs to the endothelial surface is not mediated by platelets or leukocytes. Brightfield (E), fluorescent (F), and merged (G) intravital microscopy imaging was performed on FeCl₃-induced RBC adhesion in murine mesenteric venules (rhodamine 6G injected). Arrowheads indicate the locations of firm adhesion points. The time course is approximately 3 minutes following FeCl₃ application. (H-I) SEM imaging shows an elongated RBC (H) and RBC fragments (I) directly adherent to the carotid endothelial surface 1 minute following FeCl₃ application.