Figure 2.

Illustration of symmetric cell division (left) and asymmetric cell division (right) in the ventricular zone of the prospective telencephalon. Progenitor cells (green), also known as radial glial cells, have elongated cell processes that are attached to the ventricular and pial surfaces and form a pseudostratified epithelium. Cell nuclei move toward the pial surface during DNA synthesis and then toward the ventricular surface just before mitosis. In early phases of cortical development, symmetric division gives rise to two identical daughter cells that are both progenitor cells (progenitor renewal). Later in development, asymmetric division (corticogenesis) produces a progenitor cell and a post-mitotic neuron (blue).