Control of follicular maturation by the combination of cellular interaction and gonadotoropin

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1.Effects of ovarian theca cells and follicle-stimulating hormone on granulosa cell differentiation during gonadotropin-independent follicular growth in cattleWe investigated the effects of theca cells or FSH on granulosa cell differentiation and steroid production during bovine early follicular growth, using a co-culture system in which granulosa and theca cells were cultured on opposite sides of a collagen membrane. Follicular cells were isolated from early antral follicles (2-4mm) that were assumed to be in gonadotropin-independent phase and just before recruitment into a follicular wave. Granulosa cells were cultured under serum-free conditions with and without theca cells or recombinant human FSH to test their effects on granulosa cell differentiation. This study verified that theca cells are involved in both rate-limiting steps in estrogen production ; i.e., androgen substrate production and aromatase regulation, and that theca cell-derived factors regulate estradiol and progesterone production in a way that reflects steroidogenesis during the follicular phase of the estrous cycle.2.Differentiation of ovarian stromal cells in vitro : Effect of granulosa cellson the theca cell recruitment in cattleFormation of a theca cell (TC) layer is one of the most important physiological events during early follicular growth. However, little is known about the mechanisms of the TC recruitment from undifferentiated ovarian stromal cells. In this study we have verified that GC are involved in functional differentiation and acquisition of LH responsiveness of stromal cells from the ovarian cortex.