Disruption of proper radial migration of cortical neurons and inhibition of Pea3-Ets transcription factor expression by suppression of FGFR-mediated activities. A-F, Representative coronal sections of E15.5 cerebral cortex after the electroporation of either EYFP alone (A-C) or FGFR3c-Δ C (D-F) together with EYFP at E12.5. C, F, Quantitative analyses of percentages of number of cells distributed at each zone. Each data point represents mean ± SEM counted in >30 sections. Images are obtained from >20 electroporated embryos. Scale bar, 0.2 mm. G-L, Hierarchical relationships between FGFR3 and Pea3-Ets transcription factors in the suppression of radial migration of cortical neurons were analyzed. Representative coronal sections of E14.5 cerebral cortex after the electroporation of FGFR3c-Δ TM construct at E12.5, showing the electroporated side (J-L) and the contralateral side (G-I) of telencephalic vesicles. Electroporation of FGFR3c-Δ TM construct in conjunction with EYFP construct at E12.5 into the ventricular zone of the lateral neocortex repressed Erm and Er81 expression in the ventricular zone at E14.5 (K, L). Fluorescent images of adjacent coronal sections are shown in G and J. Images are representative of > 10 electroporated samples. Images in G-I were processed to show mirror images for the ease of comparison with the images of J-L using Photoshop. Scale bar, 0.2 mm.