Schematic representation of results obtained in this study. The left-hand drawings represent the pattern of Neurog2 expression in the mouse OB, RMS and dorsal wall of the lateral ventricle at the developmental stages analyzed in this study (E13.5, E17.5 and P0). Note that at all stages progenitors sequentially and transiently express Pax6, Neurog2, Tbr2 and Tbr1. The right drawings are neurolucida reconstructions of mature neurons produced at these different developmental stages. Note the different morphologies. All neurons express Tbr2 independently of their date of birth, but only neurons generated at late developmental stages also express Tbr1.