Figure 4.

Electroporation of morpholino oligo into placode-derived cells. Control (A) or antisense (B) morpholino oligo are detected in placodes and placode-derived cells of the VIIth, IXth, and Xth nerves. Embryos electroporated with control (C,E,G,I) or antisense (D,F,H,J) Morpholino oligo were double-stained (E,F,I,J) for ISLET-1 (green) and neurofilaments (red); only single fluorescein images for ISLET-1 are shown in “C,” ”D,” ”G,” and ”H.” In control embryos (C,G), placode-derived cells of the VIIth, IXth, and Xth nerve have migrated dorsally (small arrowheads); but in embryos electroporated with antisense oligo (D,H), the migration of these cells has been disrupted (D, brackets; H, small arrowheads). Neurofilament staining shows that in antisense oligo-containing embryos, the VIIth (arrow in “F”) and IXth (large arrowhead in “F”) nerve fibers are thinner than those of the control embryo (arrow and large arrowhead in “E”) and that the Xth nerve connection to the neural tube has been affected (bracket in “J”). Large arrowheads in “I” and “J” indicate the IXth nerve fibers. (K,L) DiI-injected embryos after electroporation. In control embryos (K), placode-derived cells of the Xth nerve have migrated dorsally (arrowheads). In embryos electroporated with antisense MO (L), these cells didn't migrate dorsally, and some of them moved towards the placode-derived cells of the IXth nerve (arrowheads).