A niche maintaining germ line stem cells in the Drosophila ovary

Stromal cells are thought to generate specific regulatory microenviroments or "niches" that control stem cell behavior. Characterizing stem cell niche s in vivo remains an important goal that has been difficult to achieve. The individual ovarioles of the Drosophila ovary each contain about two germ l ine stem cells that maintain oocyte production. Here we show that anterior ovariolar somatic cells comprising three cell types act as a germ line stem cell niche. Germ line stem cells Lost by normal or induced differentiation are efficiently replaced, and the ability to repopulate the niche increase s the functional lifetime of ovarioles in vivo. Our studies implicate one o f the somatic cell types, the cap cells, as a key niche component.