In vitro maturation of oocytes

Only about 400 of the one million oocytes present at birth will be ovulated , while the rest will die by atresia. The ability to rescue oocytes destine d to die and mature them in vitro would provide invaluable information abou t folliculogenesis and oocyte maturation, and could provide oocytes for inf ertile women. In vitro maturation (IVM) is challenging in the human because folliculogenesis is a lengthy process encompassing many complex cellular c hanges in the oocyte and its surrounding follicle cells. A few live births have resulted from the maturation and fertilization of immature human oocyt es aspirated from small antral follicles. Furthermore, it is possible to gr ow primordial follicles to pre-antral stages in slices of ovarian tissue, a nd support antrum formation in isolated pre-antral follicles. However, we a re still a considerable way from growing and maturing pre-antral follicles to pre-ovulatory stages in vitro. The importance of the follicular environm ent for producing a healthy and developmentally competent oocyte is illustr ated by the oocyte's susceptibility to errors during meiosis. This counsels considerable caution in the development of IVM for clinical application.