Functional differentiation in progesterone secretion by granulosa versus cumulus cells in the human preovulatory follicle and the effect of different induction of ovulation protocols

Abstract

To investigate P secretion by granulosa cells (GCs) versus cumulus cells derived from human preovulatory follicles. Cells were recovered by aspiration of preovulatory follicles in 44 women participating in an IVF program. Induction of ovulation was performed using clomiphene citrate, hMG and hCG (group I), hMG/hCG (group II), buserelin acetate/hMG/hCG (group III), or Decapeptyl/hMG/hCG (group IV). Laboratories of the IVF Unit at the Department of Obstetrics and Gynecology, Carmel Medical Center, Haifa, Israel. Secretion of P was examined after cultures for 96 hours under nonstimulated and hCG stimulated conditions. Progesterone secretion by GCs derived from all four groups was found to be higher compared with the respective cumulus cells. However, although the ratios of P secretion by GCs versus cumulus cells in groups I, II, and III were very similar, a significantly lower value was observed in group IV. The response of GCs to hCG in terms of P secretion was higher with at least one dose of hCG in groups I and IV compared with groups II and III. The response of cumulus cells to hCG was absent regardless of the treatment protocol used in vivo. Our results demonstrate that in the human preovulatory follicle, GCs and cumulus cells differ in their capacity to secrete P as well as in their response to hCG. They further suggest that the mode of induction of ovulation affects the relative capacity of GCs and cumulus cells to secrete P and their ability to respond to hCG.