Normal neuronal migration in the mammalian cortex. A. Snapshots of the neuronal migration simulation. Radial progenitor glial cells (pink) proliferate asymmetrically giving rise to neuroblasts (red). Neuroblasts migrate radially on the glial fiber. Neuroblasts adopt a multipolar stage (green) and migrate independently from the glial fiber. Multipolar neurons re-associate with the glial fiber, enter the bipolar migration (yellow) and accumulate on the pile surface. B. Histology of the mouse cortex at embryonic day 16 (reproduced with permission from ).