NEURAL STEM-CELLS IN THE ADULT MAMMALIAN FOREBRAIN - A RELATIVELY QUIESCENT SUBPOPULATION OF SUBEPENDYMAL CELLS

Dissection of the subependyma from the lateral ventricle of the adult mouse forebrain is necessary and sufficient for the in vitro formation of clonally derived spheres of cells that exhibit stem cell propertie s such as self-maintenance and the generation of a large number of pro geny comprising the major cell types found in the central nervous syst em. Killing the constitutively proliferating cells of the subependyma in vivo has no effect on the number of stem cells isolated in vitro an d induces a complete repopulation of the subependyma in vivo by relati vely quiescent stem cells found within the subependyma. Depleting the relatively quiescent cell population within the subependyma in vivo re sults in a corresponding decrease in spheres formed in vitro and in th e final number of constitutively proliferating cells in vivo, suggesti ng that a relatively quiescent subependymal cell is the in vivo source of neural stem cells.