Fig. 6. Ebf acts as a dominant-negative mutant and impairs neuronal differentiation. (A-D) Flat-mounted hindbrains from chick embryos that were not electroporated (A) or were co-electroporated at stage HH10 with the indicated constructs (B-D) and the GFP expression vector, then collected 24 hours later and processed for neurofilaments immunochemistry. The examples shown are representative of more than 90% of the embryos, from six independent experiments, each involving at least eight embryos. (E-H) Transverse sections from stage HH15 embryos that were co-electroporated with Ebf and GFP expression vectors, collected 30 hours later and processed for whole-mount in situ hybridisation with CRABPI (E), Islet1 (F), Ngn2 (G) and NeuroM (H) probes. The cases shown are representative of more than 80% of the embryos, from four independent experiments, each involving at least eight embryos per probe. Electroporation was on the right side. Note that Ebf blocks neurofilament induction promoted by Ebf1 and reduces the level of late (CRABPI, Islet), but not early (Ngn2, NeuroM), neurogenesis markers.