Fig. 5. Time-lapse analyses of defective migration of the nVII motor neurons. (A-D) Time-lapse observations of migrating nVII motor neurons in hindbrain explants of the wild-type (A), olt (B,C) and ord (D) Isl1-GFP embryos at the time (hpf) indicated in each panel. (Also see Movies S1-S5 in the supplementary material.) Images are composite stacks of serial optical sections. (A,B,D) Lateral views with anterior to the left; the inner lumen of the otic vesicle (ov) is indicated by broken lines. (C) Frontal views at r4. In the olt embryos, all neurons failed to migrate caudally (B) but mismigrated towards the ventricle (arrows in C) by extending aberrant radial processes (arrowheads in C). In the ord embryo, some of the late-born nVII motor neurons (indicated by arrows in D) migrated caudally in the dorsal part of the hindbrain. nV, trigeminal motor neurons; VIIn, facial motor axons. Asterisks indicate the r6-derived putative octavolateralis efferent (Ole) neurons (Wada et al., 2005). Scale bar: 50 µm.