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Follicle-stimulating hormone (FSH) and oocyte-secreted factors influence granulosa cell differentiation and follicle development. Whereas FSH stimulates the expression of mural cell transcripts, oocyte-secreted factors regulate specific cumulus cell genes and suppress the appearance of mural cell transcripts. This study addresses the extent to which clinically relevant changes in FSH doses applied during antral follicle development in vitro could alter the expression of oocyte and cumulus cell transcripts. A 12-day culture system in which mouse ovarian preantral follicles can grow to preovulatory follicles was used. The following three FSH regimens were considered: 1) continuous exposure to an FSH level of 10 mIU/ml (control), 2) decreasing concentrations of FSH (low FSH), and 3) an FSH level of 25 mIU/ml (high FSH) as soon as the antrum is formed. Transcripts in oocytes (Gdf9, Bmp15, and Fgf8) and in …