Formation of ovarian follicles in ruminants

Abstract

The ovarian follicle is a key component for determining a female's reproductive potential; however, the mechanisms regarding the factors that control formation of follicles are not well understood. Within a species, the number of follicles formed in the ovary can vary considerably among individuals. While we are beginning to better characterize the processes required for follicle formation, much still needs to be determined regarding the factors that control these processes. It is clear that both genetic and environmental factors influence the formation of the follicles and number of follicles formed; but the identity and relative role of many of these factors is still unknown. Furthermore, the relationships between events occurring during follicle formation and the animal's future reproductive potential are just beginning to be explored. In this review, we have focused on the process of follicle formation in domestic ruminants, using the sheep and cow as models. We first describe the events during ovarian formation leading up to and including follicle formation and then explore a few factors that may control these processes.