Vascular niche for adult hippocampal neurogenesis

The thin lamina between the hippocampal hilus and granule cell layer, or su bgranule zone (SGZ), is an area of active proliferation within the adult hi ppocampus known to generate new neurons throughout adult life. Although the neuronal fate of many dividing cells is well documented, little informatio n is available about the phenotypes of cells in S-phase or how the dividing cells might interact with neighboring cells in the process of neurogenesis . Here, we make the unexpected observation that dividing cells are found in dense clusters associated with the vasculature and roughly 37% of all divi ding cells are immunoreactive for endothelial markers. Most of the newborn endothelial cells disappear over several weeks, suggesting that neurogenesi s is intimately associated with a process of active vascular recruitment an d subsequent remodeling. The present data provide the first evidence that a dult neurogenesis occurs within an angiogenic niche. This environment may p rovide a novel interface where mesenchyme-derived cells and circulating fac tors influence plasticity in the adult central nervous system. (C) 2000 Wil ey-Liss, Inc.