Fig. 3. Early markers of RBs are eliminated by ngn1 MO. (A,C,E,G,I) Uninjected embryos. (B,D,F,H,J) Embryos injected at the one- to two-cell stage with 1.5 ng of ngn1 MO. (A,B) Embryos fixed at the five-somite stage (about 12 hpf), processed to reveal isl1 RNA expression. RBs (arrowheads, RB) and trigeminal ganglion precursors (tri) were highly reduced, whereas PMNs and hatching gland (HG) were still present in injected embryos (25 embryos scored). (C,D) Embryos fixed at the five-somite stage, processed to reveal neurod (nrd) RNA expression. RBs (arrowheads) and trigeminal ganglion precursors (tri) were highly reduced in injected embryos (24 embryos scored). (E,F) Embryos fixed at the three-somite stage (about 11 hpf), processed to reveal dla expression (left half of neural plate is shown). High level expression, identifying RB precursors (arrowheads) and trigeminal ganglia (tri) was eliminated, whereas low level expression in lateral neural plate and trigeminal ganglia was still present in injected embryos. Medial neural plate expression at high and low levels was present in injected embryos (43 embryos scored). (G,H) Embryos fixed at 24 hpf and processed to reveal zn12 antibody immunoreactivity in RBs. RBs were highly reduced or completely absent from injected embryos, although residual labeling was still visible in unidentified cell bodies and axon tracts within the intermediate spinal cord and hindbrain (28 embryos scored). (I,J) Embryos fixed at 24 hpf and processed to reveal zn1 and znp1 antibody immunoreactivity. PMN axons are labeled and appear normal in number in injected embryos (26 embryos scored). Scale bars: 100 µm in A-F; 50 µm in G-J.
