Subventricular zone - site of neurogenesis

http://en.wikipedia.org/wiki/Subventricular_zone

The SVZ is a known site of neurogenesis and self-renewing neurons in the adult brain,^[7] serving as such given the interacting cell types and extracellular molecules promoting such cellular proliferation. Along with the subgranular zone of dentate gyrus, the subventricular zone serves as a source of neural stem cells in the process of adult neurogenesis. It harbors the largest population of proliferating cells in the adult brain of rodents, monkeys and humans.^[8] In 2010, it was shown that the balance between neural stem cells (NSCs) and neural progenitor cells (NPCs) is maintained by an interaction between the epidermal growth factor receptor signaling pathway and the Notch signaling pathway.^[9]

While it has yet to have been studied in-depth in the human brain, the SVZ function in the rodent brain has been, to a certain extent, examined and defined for its abilities. With such research, it has been found that the dual-functioning astrocyte is the dominant cell in the rodent SVZ; this astrocyte acts as not only a neuronal stem cell, but also as a supporting cell that promotes neurogenesis through interaction with other cells.^[4] This function is also induced by microglia and endothelial cells that interact cooperatively with neuronal stem cells to promote neurogenesis in vitro, as well as extracellular matrix components such as teneascin-C (helps define boundaries for interaction) and Lewis X (binds growth and signaling factors to neural precursors).^[10] The human SVZ is different, however, from the rodent SVZ in two distinct ways; the first is that the astrocytes of humans are not in close juxtaposition to the ependymal layer, rather separated by a layer lacking cell bodies; the second is that the human SVZ lacks chains of migrating neuroblasts seen in rodent SVZ, in turn providing for a lesser number of neuronal cells in the human than the rodent.^[2] For this reason, while rodent SVZ proves as a valuable source of information regarding the SVZ and its structure-to-function relationship, the human model will prove significantly different.