SEPARATE PROGENITORS FOR RADIAL AND TANGENTIAL CELL DISPERSION DURINGDEVELOPMENT OF THE CEREBRAL NEOCORTEX

Cell lineage analyses suggest that cortical neuroblasts are capable of undertaking both radial and tangential modes of cell movement. Howeve r, it is unclear whether distinct progenitors are committed to generat ing neuroblasts that disperse exclusively in either radial or tangenti al directions. Using highly unbalanced mouse stem cell chimeras, we ha ve identified certain progenitors that are committed to one mode of ce ll dispersion only. Radially dispersed neurons expressed glutamate, th e neurochemical signature of excitatory pyramidal cells. In contrast, tangential progenitors gave rise to widely scattered neurons that are predominantly GABAergic. These results suggest lineage-based mechanism s for early specification of certain progenitors to distinct dispersio n pathways and neuronal phenotypes.