Stage-dependent role of growth differentiation factor-9 in ovarian follicle development

GDF-9 was shown to be essential for follicle progression and is the only fa ctor secreted by the oocyte shown to increase the number of primordial and primary follicles in vivo. Furthermore, GDF-9 is a major growth factor invo lved in the oocyte control of granulosa cell differentiation. A concentrati on gradient of the paracrine factor GDF-9 established by the oocyte could p rovide the basis to explain the stratification of granulosa cells in antral and preovulatory follicles. The stimulatory effects of GDF-9 on early foll icle development provide a basis for the use of GDF-9 in the treatment of i nfertility. (C) 2001 Published by Elsevier Science Ireland Ltd.