Endocrine and Local Regulation of Testicular Hormone and Sperm Production

Abstract

The testis has two main functions, that is, androgen production and spermatogenesis, and the key role in their endocrine regulation is played by the two pituitary gonadotrophins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates Leydig cells of testicular interstitial tissue in the production of testosterone (T). T, secreted into the peripheral circulation, regulates the function of an array of androgen-responsive non-gonadal target tissues. Within the testis, T regulates indirectly spermatogenesis through stimulation of Sertoli cells in the seminiferous tubules. FSH promotes spermatogenesis, also indirectly, through actions on Sertoli cells. A plethora of local paracrine signals and metabolites between Sertoli and germ cells underlie the intricate regulatory mechanisms of spermatogenesis. This chapter summarizes the main hormonal regulation of the testis, that is, the hypothalamic–pituitary–testicular axis, and the main events in the process of spermatogenesis and its regulation.