Current states of endogenous stem cells in adult spinal cord.

New neurons are continuously generated throughout life in the subgranular zone in the dentate gyrus of the mammalian hippocampus and in the subventricular zone of the lateral ventricles. With the aid of new methodologies, significant progress has been made in the characterization of endogenous stem cells (ependymal cells) and their development in the adult spinal cord. Recent studies have shed light on essential extrinsic and intrinsic molecular mechanisms that govern sequential steps of neurogenesis in the adult spinal cord. This review discusses the occurrence, origin, and specific makers of ependymal cells; the factors regulating neurogenesis of multipotent ependymal cells; and the implications of ependymal cells in the repair of spinal cord injuries.