Preovulatory follicle contributions to oocyte competence in cattle: importance of the ever-evolving intrafollicular environment leading up to the luteinizing hormone surge.

Bovine pregnancy rates and oocyte developmental competence are heavily influenced by the periovulatory follicular environment. It is well known that the status of the preovulatory follicle at the time of the luteinizing hormone (LH) surge is related to both circulating and intrafollicular hormone concentrations during the follicular phase. Additional relationships between follicle status at the time of the LH surge and oocyte metabolic capacity or modifications in the follicular fluid metabolome and proteome have recently been established. Such studies suggest that critical, multifaceted modifications to the intrafollicular components occur leading up to the LH surge, and that such modifications contribute to the optimal preparation of both the oocyte and intrafollicular environment for oocyte maturation. This review focuses on intrafollicular changes that occur within the dominant follicle from luteolysis to the LH surge and discusses recent advancements in the literature related to how such changes support oocyte competence.