[Cell biology and physiology of male reproduction].

Background: An adequate and undisturbed generation of fertile sperm is a prerequisite for fatherhood. Therefore, spermatogenesis is of central importance for male fertility. The testes, however, not only hold the germinal epithelium as the sperm-generating organ but also acts as a gland releasing androgens to control male reproductive function. This dual testicular function provides options to couple and coordinate spermatogenesis and steroidogenesis.

Methods: The regulation of both processes via the hypothalamus-pituitary-gonadal axis is arranged via feedback loops, which are interconnected but also enable separate modulation of germ cell production and endocrine activity. Many parameters of gonadal function can be determined and provide information about physiological or pathological changes of testis function.

Objectives: This article introduces the physiological basics of testis function and presents the repertoire of endpoints determined in clinical andrology to facilitate a deeper understanding for clinical diagnostics of male fertility.