Named after Enrico Sertoli, an Italian physiologist, Sertoli cells are a specialized cell type found in the testicles. Specifically, they are located in the seminiferous tubules of the testes and they facilitate the production of new sperm, or, spermatogenesis.
Sertoli cells have many functions. One function is secreting a number of substances that maintain and stimulate spermatogenesis. Among these substances is androgen binding protein which increases testosterone concentration in the seminiferous tubules, and stimulates spermatogenesis. A number of other hormones and compounds are also produced, all of which are involved in nourishing sperm cells through to later stages of spermatogenesis.
Sertoli cells are also responsible for formation of the blood-testis barrier, which partitions blood flow from the seminiferous tubules. This physical barrier is not a strict barrier, but rather is formed by the very tight junctions between individual Sertoli cells.
Other functions of Sertoli cells include DNA repair, phagocytosis, and the modulation of immune response. All of these functions are involved in the differentiation of spermatogonia into mature sperm.
Sertoli cells are also required for male sexual development, and in puberty, once spermatogenesis has begun, Sertoli cells are unable to proliferate. This means from that point on, no more Sertoli cells are created, and any damage to existing Sertoli cell populations can be permanent.