The human brain subventricular zone: stem cells in this niche and its organization.

The human brain harbors stem cells in the subventricular zone (SVZ). The authors have collected postmortem and intraoperative tissue from adult human patients and found that it contains a unique ribbon of astrocytes that proliferate in vivo and can function as neural stem cells in vitro. Furthermore, they have conducted an anatomic, cytoarchitectural, and ultrastructural study in complete postmortem brains to define the precise organization of the lateral walls of the human lateral ventricles. With immunohistochemistry, the authors mapped a proliferative glial fibrillary acidic protein (GFAP)--positive ribbon of astrocytic cells in the human SVZ. In this article, the authors report on four main types of SVZ walls in the human brain. Types A through C line the striatum from dorsal (type A), to middle (type B), to ventral (type C) regions along the lateral wall of the lateral ventricle. Type D wall lines the floor of the temporal horn over the hippocampus. Understanding the organization of the adult human SVZ represents a necessary first step in understanding cellular proliferation, precursor migration, and the neurogenic niche of the largest known germinal region in the adult human brain.