Increased postovulatory plasma follicle stimulating hormone levels in the luteinized unruptured follicle syndrome: a role for inhibin?

In women who ovulated, the midcycle plasma follicle stimulating hormone (FSH) concentrations returned to basal concentrations within two days following the peak, whereas in women with a luteinized unruptured follicle, plasma FSH concentrations declined more slowly over a 4-5 day period. Since the peri- and postovulatory concentrations of plasma luteinizing hormone, prolactin, oestradiol-17 beta and progesterone were not significantly different between the two groups, we suggest that following the rupture of the Graafian follicle some substance in follicular fluid is resorbed from the peritoneal cavity which suppresses FSH secretion. Inhibin has biological properties which suggest it could be the substance involved.