The actions of follicular fluid factors on steroidogenesis by cultured ovarian granulosa cells.
Fluid from porcine follicles alters estrogen and progesterone secretion by porcine granulosa cells in vitro. The specific actions of the follicular fluids depend on the size of the follicles from which both the fluid and the cells are obtained. Fluid from large, primarily preovulatory follicles enhances both basal estrogen secretion and basal and hormonally stimulated progesterone secretion by cells from small follicles. Estrogen secretion by cells from larger follicles is also enhanced but fluid from large follicles is only equivalent to serum in supporting progesterone secretion by these more mature cells. Fluid from small follicles exhibited weak stimulatory actions on cells from small follicles but inhibited basal and hormonally stimulated progesterone secretion by cells from larger follicles. A hypothetical model is proposed for a physiological role for the stimulatory and inhibitory follicular fluid factors. Only those small follicles containing the stimulator become sufficiently responsive to gonadotrophins and produce adequate estrogen to allow further follicle maturation. The remaining small follicles possess the inhibitor which blocks responsiveness to gonadotrophins, and contributes to atresia. Many questions remain concerning the identity of the factors, which cells produce them and how their production is controlled.
D000818:Animals; D002478:Cells, Cultured; D004967:Estrogens / Q000096:biosynthesis* / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000502:physiology*; D007986:Luteinizing Hormone / Q000494:pharmacology; D006080:Ovarian Follicle / Q000378:metabolism*; D010060:Ovulation; D011374:Progesterone / Q000096:biosynthesis* / Q000378:metabolism; D011458:Prostaglandins E / Q000494:pharmacology; D013552:Swine; D013739:Testosterone / Q000494:pharmacology
D004967:Estrogens; D011458:Prostaglandins E; D013739:Testosterone; D011374:Progesterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone