Fig. 5

Fgf3 and Fgf10a are required for placode maturation and neurogenesis.

(A-F) Uninjected and fgf10a-MO injected progeny from fgf3+/-;TgBAC(neurog1-DSRed) crosses were collected at 36 hpf and immunolabeled for Pax2a and DSRed to visualize EB placodes and migrating neuroblasts, respectively. Wild-type (A) and fgf3+/- (B) panels shows neurog1:DSRed+ cells undergoing neurogenesis (magenta) at the dorsal aspect of the mature Pax2a+ EB placodes (green; dotted line). fgf3-/- embryos show a loss of properly formed Pax2a+ EB placodes in the region of the prospective glossopharyngeal and three small vagal ganglia and a concurrent loss of neurog1:DSRed+ cells in this region (C; bracket); however, the facial and large vagal placode/ganglia are still present (arrowheads). Analysis of fgf10a-MO injected wild-type (D) and fgf3+/- (E) embryos reveal ectopic neurogenesis as marked by neurog1:DSRed+ cells ventral to the posterior most aspect of the vagal placode (arrow). fgf3-/-;fgf10-MO embryos show a complete loss Pax2a expression in EB placodes and an absence of neurogenesis, except for a few neurog1:DSRed+ cells near the region of the large vagal ganglia (F; asterisk). Abbreviation: ngn:dsred, TgBAC(neurog1-DSRed); f, facial placode; g, glossopharyngeal placode; v, vagal placodes. Scale bar: 50 μm.