Fig. 2

Neuronal hyperplasia in wit^ta52b. All are dorsal views and rostral to the left, except for G and H, which are lateral views and rostral to the top. Hindbrain reticulospinal neurons in wild-type (A) and mutant (B) embryos labeled with mAb 3A10 at 36 hpf. Anterior parts of wild-type (C) and mutant (D) embryos and of trunk parts of wild-type (E) and mutant (F) embryos labeled with Islet-1 antibody at the 8-somite stage. Wildtype (G) and mutant (H) embryos labeled with Islet-1 antibody at 20-somite stage. The presumptive anterior lateral line ganglion (arrowhead) and presumptive posterior lateral line ganglion (arrow) are indicated. pax-b expression in wild-type (I) and mutant (J) embryos at 24 hpf. The CoSA neurons (arrowheads) and pronephric duct (arrows) are indicated (Mikkola et al., 1992). In mutant embryos, not only is the pax-b expression in spinal interneurons and pronephric duct increased, and there is also an increased expression in presumptive r2, r3 and r4 (asterisks). dr, dorsorostral cluster; e, epiphysis; M, Mauthner cell in r4; mhb, midbrain-hindbrain boundary; mlf, medial longitudinal fascicle; mn, primary motoneurons; op, otic placode; os, optic stalk; ov, otic vesicle; p, polster; rb, Rohon-Beard cells; RoL2, RoL2 neurons in r2; tg, trigeminal ganglia; vr, ventrorostral cluster. Bar, 100 µm (A,B); 160 µm (CF); 255 µm (G,H); 400 µm (I,J).