Fig. 3. Notch1a^ac expression blocks neurogenesis. Transverse sections, dorsal to top, labeled by immunocytochemistry to reveal Hu proteins. (A) Wild-type control embryo revealing normal distribution of neurons at 48 hpf. (B) 48 hpf transgenic embryo, in which Notch1a^ac expression was induced at 10, 24 and 36 hpf, had a deficit of neurons. Scale bar: 20 µm.