Acentric separation and segregation is delayed relative to intact chromosomes. (A) Still images from a time-lapse movie of a mitotic neuroblast without I-CreI. Chromosomes are labeled with H2Av-RFP. (B) Images from a time-lapse movie of a mitotic neuroblast with I-CreI–induced acentrics (Video 1). Acentrics (arrowheads) are pushed to edge of plate at 0 s. Acentrics lag on the spindle equator (0–190 s) but eventually move poleward (230–400 s). Bars, 2 µm. Time in seconds.