Half a decade ago, we witnessed the culmination of much of what we comprehend today in classical ovarian endocrinology and physiology [1;2], human embryology [3] as well as clinical ovarian ultrasonography [4]. Much of the former was based upon the development of (radio-)immunoassays that could reliably detect low concentrations of hormones in body fluids, including the peripheral circulation. This meant that correlations of hormone concentrations and specific physiological events could be determined with precision, leading to many advances in clinical practice and drug development. The biological control of all these physiological elements is, of course, gonadotropin-releasing hormone (GnRH), whose decapeptide structure was elucidated by Andrew Schally and colleagues in 1971 [5], for which he was awarded his share of the Nobel prize in 1977. His co-prize winners were responsible for the pioneering of immunological competitive binding dilution assays, which underwrote all these developments.