Fig. 3. Excess Mash1 promotes dI3 and dI5 populations, while excess Ngn2 represses them in the chick neural tube. Immunofluorescence on transverse sections of E4 (HH23-24) chick neural tubes electroporated with pMiWIII-Mash1 (A,C,E,G) or pMiWIII-Ngn2 (B,D,F,H) at E3 (HH13-14). The arrow above each row of panels indicates the electroporated side of the neural tube. Neuronal population dI2 was labeled by Brn3a;Lhx1/5 (yellow) (A,B), dI3 by Isl1 (C,D), dI4 by Pax2 (E,F) and dI5 by Lmx1b (G,H). Each panel is representative of the phenotype seen in at least three sections from at least three electroporated embryos. (I) Relative induction or repression is expressed as the number of cells on the injected side divided by the number of cells on the control side and plotted in the graph on a logarithmic scale. ^** P<0.001. Scale bar: 25 µm.