Peripheral and local regulators of folliculogenesis.

The role of the gonadotrophins follicle-stimulating hormone (FSH) and luteinizing hormone and the putative local regulators, activin and follistatin, in the control of folliculogenesis is reviewed. An account of early work on the development and application of assays for FSH and inhibin is given, together with a summary of the data on the ovarian responsiveness to gonadotrophin and follicular atresia. Models for studying local regulation of granulosa cells in vitro are described and the data from these experiments reviewed. It is concluded that activin has a role in the development and maintenance of healthy oestrogenic follicles, preventing premature luteinization, whereas follistatin opposes these effects of activin and promotes luteinization or atresia.