Inhibin and activin represent THF-β growth factors, a family of compounds of a similar chemical structure but significantly different function. Inhibin is produced in the granular cells of the ovarian follicles as well as in the luteal cells of the corpus luteum. The presence of activin was confirmed in the granular cells, hypophysis and hypothalamus. The basic physiological function of these glycoproteins is controlling the hypothalamus-hypophysis-ovaries feedback axis. Inhibin is a renowned neoplastic marker in assessing the efficacy of the surgical treatment, in monitoring and detection of early relapses in patients with granulosa cell tumours. Using RIA tests, elevated inhibin concentrations can be detected in about 80% of the patients with mucous epithelial neoplasms of the ovary. Activin is also likely to be a valuable marker, especially in diagnosing a recurrence of the disease. Both inhibin and activin are involved in the process of proliferation in ovarian cancers. In experimental mice deprived of inhibin, a rapid growth of the tumours occurs, which, in turn, implies that this compound is a negative regulator of proliferation. Simultaneously, high FSH concentrations prove that gonadotropins take an active part in the ovarian carcinogenesis.
Unlike inhibin, which seems to protect from high gonadotropin concentrations and inhibit proliferation, activin is considered in numerous studies to be a factor that intensifies proliferation of the ovarian cancer cells, hence contributing to the disease progression.