Sertoli cells are specialized cells in the seminiferous tubules that support the production of sperm cells. Together they form the blood-testicular barrier, which divides the seminiferous tubules into two compartments and creates a protective, nourishing environment for spermatogenesis. Sertoli cells also function as phagocytes to clear excess cytoplasm and apoptotic sperm cells from the seminiferous tubules and play a central role in the sexual differentiation of human embryos.
What is a Sertoli cell?
Sertoli cells are specialized epithelial cells in the seminiferous tubules of the male testicle. They are the supporting cells for spermatogenesis and their main job is to protect and nourish the germ cells as they develop into sperm. They also produce Androgen binding protein, the testosterone in the seminiferous tubules binds and concentrates.
Location of the Sertoli cells
Sertoli cells line the epithelium of the seminiferous tubules of the male testicle, where spermatogenesis takes place.
Functions of Sertoli cells
Sertoli cells are located in the seminiferous tubules of the male testes, where they have various functions in helping sperm development.
Support of spermatogenesis
Sertoli cells are often referred to as “nurse cells” because of their role in helping sperm develop in the testes. Mature sperm develop through meiosis from germ cells in the seminiferous tubules. Sertoli cells form protective pockets around the germ cells and release nutrients to support their development into spermatozoa.
Sertoli cells also act as phagocytes, removing apoptotic sperm and excess cytoplasm from the seminiferous tubules. Residual cytoplasm is a by-product of spermatogenesis, and apoptosis is a fate that affects more than half of developing sperm cells before they reach maturity. Therefore, Sertoli cells play an important role in removing unwanted materials from the seminiferous tubules.
Androgen Binding Protein (ABH) production
Another important function of Sertoli cells is to produce androgen binding protein (ABP); a glycoprotein that specifically binds to testosterone. ABP increases the testosterone concentration in the seminiferous tubules, which is essential for the complete maturation and release of the sperm cells. Therefore, ABP is a crucial part of spermatogenesis
Male embryonic development
Sertoli cells play a central role in the sexual differentiation of human embryos, which occurs 6 weeks after fertilization.
Sertoli cells develop in response to a signal from a gene on the Y chromosome and initiate the development of testes in male embryos. They also secrete a hormone called anti-Muller hormone (AMH), which suppresses the development of female reproductive organs and germ cells.
Leydig cells (another specialized cell in the testes) secrete testosterone, which helps the male reproductive organs develop. Therefore, both Sertoli cells and Leydig cells are crucial for male embryonic development.
Sertoli cells and the blood-testicular barrier
Sertoli cells are connected by continuous tight junctions that form the blood-testicular barrier.
The blood-testicular barrier divides the seminiferous tubules into two compartments; the basal compartment and the adluminal compartment. The basal compartment contains spermatogonia (ie, male germ cells), and the adluminal compartment houses developing sperm cells. Because large molecules cannot cross the blood-testicular barrier, the adluminal compartment is effectively isolated from the basal compartment and the blood. This creates a protective micro-environment that supports the development and maturation of the sperm cells.