Fig. 6

nVII motor neurons migrate normally in the gastrulation mutant, knypek (kny). All panels show dorsal views of the islet antibody-labeled hindbrains with anterior to the left. Embryos were from obtained from a cross of trilobite;knypek double heterozygotes. The arrowheads in (B–D) point to the most anterior spinal motor neurons. The strongly labeled, medially located cells in r5 and r6 surrounding the asterisk are the abducens (nVI) motor neurons. (A) In a 36-HPF wild-type sibling, the islet-labeled cells corresponding to the nV, nVII (arrows), and nX neurons are found at their characteristic locations. (B) In a knypek mutant, the islet-labeled cells corresponding to the nV, nVII (arrows), and nX motor neurons are found at their normal locations, as in wild-type embryos. (C) In a trilobite mutant, the nVII neurons (arrow) are found in r4. (D) In a trilobite;knypek double mutant, islet-labeled cells corresponding to putative nVII neurons (arrow) are still located in r4. The nVI neurons in r6 are missing. The nX neurons are greatly reduced in number and are positioned very laterally compared to either single mutant, reflecting the extremely reduced convergence extension cell movements in double-mutant embryos. Scale bar, 100 μm.