Involvement of Bone Morphogenetic Proteins (BMPs) in Ovarian Function and Infertility

Advances in assisted reproduction techniques and the treatment of diseases known to be correlated with infer- tility such as polycystic ovary syndrome and premature ovarian failure require a better understanding of ovarian physiol- ogy. Despite the enormous quantity of information produced over the last two decades, the mechanisms controlling fol- licular development are not fully understood. Ovarian function is regulated by interactions between gonadotropins, follicle stimulating hormone, luteinizing hormone and local ovarian factors such as inhibins, activins, bone morphogenetic pro- tein-15 (BMP-15) and growth differentiation factor-9 (GDF-9), all members of the transformation and growth factor-� (TGF-� ) superfamily. There is evidence of a functional ovarian BMP system with countless genes involved in normal fol- licular development and in fertility. The present review summarizes the ligands of the TGF-� superfamily, their receptors and signaling pathways and discusses the ovarian functions of the BMPs secreted by the oocytes as critical regulators of fertility.