Fig. 6

Fig. 6 Caudal migration of FBM neurons is not affected by loss of Dishevelled function. Ventricular (A)–(D) and pial (E)–(H) views of embryos processed for Tbx20 ISH. In E12.5 control Dvl1+/-;Dvl2+/- embryos (A), FBM neurons migrate caudally from r4 into r6 (arrowhead) to form the facial motor nucleus (nVII). This caudal migration occurs normally in Dvl1+/;Dvl2-/-(B), Dvl1-/-;Dvl2+/- (C), and Dvl1-/-;Dvl2-/- mutants (D), inspite of neural tube closure defects in many of these embryos. By E14.5, FBM neurons in control embryos (E) have completed their caudal and radial migrations to form facial motor nuclei (nVII) in r6. Likewise, these nuclei are formed in r6 in Dvl-deficient embryos including Dvl1+/-;Dvl2-/- (F, 2/2 embryos), Dvl1-/-;Dvl2+/- (G, 6/6 embryos), and Dvl1-/-;Dvl2-/- mutants (H, 4/4 embryos). Neural tube defects were seen in Dvl1-/-;Dvl2-/- mutants. I-L, Dorsal views of 48 hpf Tg(isl1:gfp) zebrafish embryos processed for anti-GFP and zn5 immunohistochemistry. In control embryos (I), GFP-expressing FBM neurons migrate caudally from r4 into r6 (arrowhead) and r7 to form the facial motor nucleus (nVII). Zn5 staining labels rhombomere boundaries. The trigeminal (nV) and vagal (nX) motor neurons are located in r2 and r3, and the caudal hindbrain, respectively. Inset shows intact embryo with normal extension of the body axis. In embryos injected with Dvl-delPDZ (J), Dvl-delC (K), and N-Daam1 (L) RNA (200 pg/embryo), FBM neurons are able to migrate caudally (arrowheads) out of r4 despite convergence and extension defects resulting in a shortened body axis (insets). Positions of the nV and nX neurons are not affected by these treatments.