ABSTRACT
The hormonal control of ovarian function by gonadotrophins plays a key part in the physiological process of follicular growth and differentiation. Over the last decade, the respective contribution of follicle stimulating hormone (FSH) and luteinizing hormone (LH) to follicular development has been better defined mainly through clinical data obtained from assisted reproductive techniques (ART) cycles performed with gonadotropin releasing hormone (GnRH) agonist protocols. More recently, the introduction of GnRH antagonists to prevent the LH surge has provided a new model for assessing the respective role of FSH and LH. In every situation, measurements of plasma concentrations of FSH and LH were used to evaluate the endocrine environment of the follicle. While it is clear that hormonal assays from blood sampling cannot adequately reflect the biological activity of gonadotrophins, this approach has allowed an assessment of the required supply of exogenous FSH and LH in ART cycles.
