Neuroblasts: a model for the asymmetric division of stem cells.

The ability of stem cells to self-renew has hung been attributed to an asymmetry in division that generates one daughter cell identical to the mother and another cell committed to differentiation. Recent studies on neuroblasts, a group of neural stem cells responsible for generating various neurons and glial cells in the central nervous system, have revealed exciting mechanisms that underlie self-renewing asymmetric division. Several important localized cell fate determinants have been characterized, and their segregation mechanism has been explored in the context of cytoskeletal organization, cell-cycle type progression, cytokinesis and mitotic orientation. These findings are illuminating in understanding the general mechanism of stem cell division.