Red blood cell evolved a mode of red blood cell development substantially different from the mammalian norm. Overall, mammalian red blood cells are remarkably flexible and deformable so as to squeeze through tiny capillaries, as well as to maximize their apposing surface by assuming a cigar shape, where they efficiently release their oxygen load. Red blood cells in mammals are unique amongst vertebrates as they do not have nuclei when mature. Red blood cells of mammals cells have nuclei during early phases of erythropoiesis, but extrude them during development as they mature; this provides more space for hemoglobin. The red blood cells without
U2 Live at Red Rocks: Under a Blood Red Sky U2 Live at Red Rocks: Under a Blood Red Sky U2 Live at Red Rocks: Under a Blood Red Sky is a concert film by Irish rock band U2. It was recorded on 5 June 1983 at Red Rocks Amphitheatre in Colorado, United States, on the group's War Tour. Originally released in 1984 on videocassette, "U2 Live at Red Rocks" was the band's first video release. It accompanied a 1983 live album entitled "Under a Blood Red Sky", on which two tracks from the film appear. The video was directed by Gavin Taylor and produced by Rick Wurpel and Doug