Fig. 3

Fig. 3 Facial (nVII) motor neuron migration is eliminated in trilobite mutants. All panels show dorsal views of the hindbrain with anterior to the left. (A–C) In a wild-type sibling (A), putative GFP-expressing nVII neurons accumulate in r4 by 18 HPF. By 24 HPF (B), nVII neurons have started migrating tangentially across rhombomere boundaries into r5, r6, and r7. By 30 HPF (C), most nVII neurons have migrated into r6 and r7. The nV neurons in r2 are induced early and remain in r2 throughout development. The nV neurons in r3 arise after 30 HPF. (D–F) In a tri mutant embryo (D), putative nVII neurons arise in r4, as in wild-type embryos. By 24 HPF (E), the number of GFP-expressing cells in r4 increases, but the cells fail to migrate tangentially (posteriorly). By 30 HPF (F), a large number of nVII neurons have accumulated in r4, and no cells have migrated into r6 and r7. Scale bar, 75 μm.