Subcellular imaging of saltatory nuclear movements in migrating THN progenitors. Lateral views of a region of the cerebellum of a 36-hpf Tg(atoh1a:Gal4TA4)^hzm2 transgenic zebrafish embryo injected with Medusa vector M1. (A–C) According to the direction of migration, the centrosome (arrow) translocates in front of the nucleus (asterisk). (C and D) The nucleus then overtakes the centrosome in a rapid saltatory movement such that the centrosome locates posterior to the nucleus (D). Subesequently, the centrosome translocates once again ahead of the nucleus (E). In a second saltatory movement, the nucleus again overtakes the centrosome (F). These time-lapse data show that during saltatory nucleokinetic migration, THN neurons display iterative cycles of a centrosome leading and trailing the nucleus. Images are maximum projections of z-stacks. The time between images taken from Video 8 is indicated in the bottom right of each panel. MHB, midbrain–hindbrain boundary; URL, upper rhombic lip.