Stem cells are maintained by signals from their local microenvironment but it has been hard to study exactly how stem cell behaviour is controlled. Now, Lucy Morris and Allan Spradling describe a culture method for live imaging Drosophila ovarian development within the germarium and use it to test some long-held beliefs about ovarian follicle development (see p. ). The germarium is a structure at the anterior tip of ovarioles that produces new ovarian follicles by controlling follicle and germline stem cell (GSC) division and nurturing their developing daughters. The researchers confirm, for example, that GSC divisions are oriented with respect to the germarium's anteroposterior axis. They also show that somatic escort cells (the glial-like partners of early germ cells) do not adhere to and migrate with GSC daughters as previously proposed, but pass the GSC daughters from one escort cell to the next using dynamic membrane activity. These and other results establish the live imaging system as a valuable tool for the study of stem cell biology.
