Stem cells in adult tissues have attracted a great deal of interest. These cells are self-renewing and can give rise to diverse progeny. An extraordinary finding was the presence of stem cells in the mature human brain. This tissue was previously believed incapable of generating new neurons, but neuropoiesis is now an established phenomenon in the adult brains of mammals, including human beings. This persistent neurogenesis has potential therapeutic applications for various neurological disorders as a source for tissue engraftment and as self-repair by a person's own indigenous population of pluripotent cells or biogenic by-products of their proliferation and differentiation.