[The behaviors of proliferative cells in the subventricular zone during cortical development]

Recent studies revealed that the subventricular zone (SVZ) in the developing mammalian cerebrum is a source of cortical neurons along with the ventricular zone (VZ), and especially in human SVZ, abundant self-renewal stem cells exist and are thought to largely contribute to the development of huge brain. These studies suggested that the regulations of the number of progenitors or stem cells in the SVZ and their stemness are important issues for understanding the final output of the cortical neurons. We previously reported the migratory difference between the direct progeny of the VZ and the further dividing cells in the SVZ in mice. The former population finishes the cell division in the VZ, stays there for more than 10 hours, and then accumulates in the lower SVZ as multipolar cells. The other exits the VZ earlier than former, distributes widely in the SVZ and divides. These observations showed that the SVZ is divided into two regions; the lower postmitotic cell accumulation region and upper dividing cell-rich region. This model provides the framework for understanding the nature of the SVZ.