Activin promotes oocyte development in ovine preantral follicles <it>in vitro</it>

Abstract

Abstract Activins have been implicated as important regulating factors for many reproductive processes. The aim of this study was to determine the effect of activin A on the development of ovine preantral follicles in vitro. Mechanically isolated preantral follicles (161 ± 2 microm) were cultured for 6 days in the presence of human recombinant activin A (0, 10 and 100 ng/ml). Half of the medium was replaced every second day and follicle diameters were measured. Conditioned medium was subsequently analysed for oestradiol content using a delayed enhancement lanthanide fluorometric immunoassay (DELFIA). At the end of the culture period, follicles were fixed and processed for histology, after which oocyte diameter and granulosa cell death were measured. There was significant follicle growth over 6 days in all groups (p in vitro, but did not accelerate follicle differentiation over a six-day culture period. These results support a paracrine role for activin A during early oocyte and follicular development.