Estrogen increases the number of newborn neurons (5-bromo-2’-deoxyuridine [green]/doublecortin [red] dual-labeled cells) in the subventricular zone (SVZ) after ischemic stroke injury. The SVZ is a major repository of neural stem cells, known to produce developing neurons that are capable of migrating to the sites of injury to potentially replace neurons that are damaged by brain injury. Although the SVZ is a promising therapeutic target for neuronal replacement therapy, the numbers of newborn neurons that actually migrate to the injury sites are believed to be too small for the functional recovery of the brain. Therefore, identification of an endogenous factor such as estrogen that stimulates neurogenesis in the face of brain insults, as well as understanding the underlying mechanisms of its action may lead to the development of neuronal restorative therapies against neurodegenerative diseases and injury.