[The multitasking Sertoli cell]

Sertoli cells (SCs) play a central role in the development of the male genital organs and are absolutely necessary in the adult testis for the maintenance of a normal spermatogenesis. They form the blood-testis barrier, which is a physical barrier between the blood vessels and the seminiferous tubules. Tight junctions between the cell membranes of adjacent SCs divide the seminiferous tubule in a basal compartment (in contact with blood and lymph) and an adluminal compartment (isolated from blood and lymph).The SCs produce more than 60 proteins, of which the most important are hormones. The anti-Müllerian hormone inhibits the development of the female Müllerian ducts in the male embryo. Inhibin inhibits the production of follicle-stimulating hormone (FSH). Activin is an antagonist of inhibin and follistatin inhibits the effect of activin. Furthermore, diverse growth factors are produced, which have auto- and paracrine effects. Androgen-binding protein makes the androgen less lipophilic and becomes more concentrated within the luminal fluid of the seminiferous tubules thus enabling spermatogenesis. Ferritin is necessary for the transport of iron to the rapidly growing germ cells.SCs selectively and rapidly eliminate apoptotic residua of spermatids through phagocytosis. Moreover, as shown in animal experiments, these cells are also able to phagocytize and kill bacteria.Sertoli cell tumors are characterized by a broad spectrum of diversity ranging from highly differentiated adenocarcinoma-like types to completely undifferentiated spindled cell variants.