Autologous granulosa cell coculture demonstrates zygote suppression of granulosa cell steroidogenesis**Presented in part at the 51st Annual Meeting of the American Society for Reproductive Medicine. Seattle, Washington, October 7 to 12, 1995.††Supported in part by Physician Scientist Award (AG00566 [D.B.S.] and R01HD31894 [A.L.S.]) from the National Institutes of Health, National Institute on Aging, Bethesda, Maryland

Oocyte-secreted factors regulate granulosa cell steroidogenesis

Investigations of strains of mice defective in germ cell development have revealed the importance of oocytes for the initial stages of folliculogenesis (Pellaset al., 1991; Huanget al., 1993). Various aspects of follicular development are dependent upon and/or influenced by the presence of oocytes, including granulosa cell proliferation (Vanderhydenet al., 1990, 1992) and cumulus expansion (Buccioneet al., 1990; Salustriet al., 1990; Vanderhydenet al., 1990; Vanderhyden, 1993). We are investigating the possibility that oocytes influence one of the primary functions of granulosa cells: steroidogenesis. In many species, granulosa cells removed from preovulatory follicles luteinisein vitro(Channinget al., 1982), presumably due to loss of contact with follicular luteinisation inhibitory factor(s). Indeed, follicular fluid can prevent granulosa cell luteinisationin vitro(Ledwitz-Rigbyet al., 1977). Follicular fluid, however, may simply be the medium for transport of factors secreted by oocytes to regulate granulosa cell activities.