Stem cells in the adult mammalian central nervous system

Over the past year, evidence has accrued that adult CNS stem cells are a wi despread progenitor cell type. These cells may normally replace neurons and /or glia in the adult brain and spinal cord, Advances have been made in und erstanding the signals that regulate stem cell proliferation and differenti ation. A deeper understanding of the structure of germinal zones has helped us move towards identifying stem cells in vivo. Recent studies suggest tha t the fate of stem cell progeny in vivo may be linked to the complexity of the animal's environment.