Sickle SS-RBCs have enhanced adhesion to rat brain microvasculature compared with control AA-RBCs. Fluorescently labeled control (AA)-RBCs (n = 5), followed by sickle (SS)-RBCs (n = 5), were infused into rats prepared with a cranial window as described in Fig 1. Cellular flow in the cortical microvessels (diameter 4 to 100 μm) was video-recorded from two to three preselected 0.07-mm2 areas within the cranial window for a total of 5 to 10 minutes. Brief adhesion events (0.1 to 1.0 second) and long adhesion events (<1.0 second) were separately quantitated (events per minute) by manual review of the video tapes. SS-RBCs had significantly increased adhesion compared with AA-RBCs for brief adhesion events (P = .0063) or long adhesion events (P = .013).