Transgenic models for exploring gonadotropin biology in the male.

Unraveling the selective actions of the two pituitary- derived gonadotropins FSH and LH in vivo is complicated by their very close structural and functional similarities, and their coordinate regulation. Both gonadotrophins are composed of a common alpha-subunit and distinct beta-subunits, which are simultaneously secreted as heterodimers in response to a single trophic hormone GnRH. Functionally, gonadotrophins interact with related receptors and share the same ultimate cellular site in the testis, the Sertoli cell with receptors for both FSH and the androgens synthesized in response to LH. This article will review the strategies to overcome these intimate connections and discuss key findings from trans-genic models developed to study gonadotropin actions in the male.