The functional maturation of the Sertoli cell and Leydig cell in the mammalian testis

Introduction The morphological features and associations of the Sertoli and Leydig cells in the adult have clear implications for their functional characteristics and for their development in the maturing testis. For example, adult Sertoli cells form intimate cellular associations with germ cells through both physical contact and gap junctions with significance for metabolic cooperation between the two cell types. Inter-Sertoli cell junctional specializations are influential in the context of the 'blood—testis barrier'. They also establish the polarity of these cells with their basal aspect against a peritubular myoid cell layer and a luminal aspect from which fluid is secreted. Leydig cells are associated with the peritubular myoid cells and with the interstitial blood vessels, being surrounded to varying extents according to species by interstitial spaces and fluid. There is a positive correlation between the amount of testosterone secreted by perfused testes in vitro of various species and the volume of