Herein, we describe the regulatory role and potential importance of GDF-8 in ovarian reproductive activity: GDF-8 expression in vivo; the role of GDF-8 in regulating reproductive functions in an in vitro GC model; association between GDF-8 expression and PCOS; relationship between GDF-8 expression and the ovarian response, pregnancy outcome of infertile women undergoing in vitro fertilization (IVF) procedures (Scheme 1). Here, MSTN is linked to polycystic ovary syndrome.