Fig. 3. Fgf3 is necessary for inducing neurogenesis in EB placodes. Embryos injected with morpholino directed against fgf3 (A-C, right) and uninjected controls (A-C, left) were processed for in-situ hybridization with ngn1, phox2a and phox2b at 36 hpf, immunolabeling with Hu antibody at 80 hpf and Zn-5 antibody at 36 hpf, and TUNEL assay at 26 hpf. All whole-mount sections show lateral views. Anterior is left. (A) ngn1, phox2a, phox2b and Hu expression were absent in the glossopharyngeal and small vagal placodes and ganglia and significantly reduced in the facial and large vagal placodes and ganglia (arrows). (B) Zn-5 staining demonstrated that pharyngeal pouches were not affected by fgf3-MO1 injection (arrowheads). (C) TUNEL assay revealed dying cells in the ectoderm of the fgf3-morphants (arrows). Insets show transverse sections through the facial placode. Scale bars: 50 µm. Abbreviations are as in Fig. 1.