The hypothalamo-pituitary-gonadal axis

This review provides an outline of how our understanding of the neuroendocrine control of the hypothalamo-pituitary-gonadal axis has evolved since the publication of Geoffrey Harris' renowned monograph in 1955. Particular attention is directed to the neurobiology underlying pulsatile GnRH release from the hypothalamus, the neuroendocrine control of ovarian cycles, puberty and seasonality of gonadal function, and to ideas that have emerged as a result of examining the relationship between growth and the reproductive axis. The review closes with i) a brief discussion of how knowledge gained as a result of pursing the early hypotheses of Harris has led to major clinical and therapeutic applications, and ii) a personal glimpse into the future of research in this fascinating area of biology.