Sequence of photographs documenting I/R-induced platelet-endothelial cell interactions in vivo. Using IVM, rhodamine-6G–labeled platelets are visualized within 3 postcapillary venules before ischemia (A), as well as following 90 minutes of ischemia and 30 minutes of reperfusion (B). Few platelets adhere to the venular endothelium before I/R (A); the majority passes the vessel segment without interacting with the endothelial surface. In contrast, a large number of platelets are seen interacting with the endothelium 30 minutes after reperfusion (B). Monitor magnification 450×; bars represent 50 μm.