Regulatory principles of follicular development

Abstract

Controlled ovarian stimulation (COS) is one of the key issues for the successful outcome of in vitro fertilization (IVF). Although retrieval of multiple oocytes is aimed at in COS, the regulatory principle governing the sequential program of follicular development in natural cycles is likely to be similar to those in stimulated cycles. In addition to the conventional pituitary-ovarian axis, the oocyte itself has now become a novel regulatory factor in folliculogenesis. As the entire process of follicular development proceeds stepwise from preantral to preovulatory stages under the infl uence of a functional interplay among these regulators, belonging to the hypothalamo- pituitary-ovarian axis, each with specifi c roles, the author intends to describe fundamental principles governing folliculogenesis fi rst and then to propose a rational and realistic idea of selecting the most appropriate stimulation protocol of the indicated ones, tailored to meet the patients ovarian reserve.