Meaning of Sertoli Cells
Sertoli cells are essential for carrying out testicular function. They are pyramidal in shape and partially involve cells of the spermatogenic lineage. The bases of the Sertoli cells adhere to the basal lamina of the tubules, and their apical ends lie in the lumen of the seminiferous tubules.
In light microscopy, Sertoli cell boundaries are poorly defined due to the large number of lateral recesses they have that encompass cells of the spermatogenic lineage.
Electron microscopy reveals that these cells have an abundant smooth endoplasmic reticulum, a poorly rough endoplasmic reticulum, a well-developed Golgi apparatus, and numerous mitochondria and lysosomes.
The core profile is triangular and has holes.
These cells are connected by gap junctions, called gap junctions, which allow ionic and chemical exchange between cells, which may be important for the coordination of the seminiferous epithelial cycle.
Adjacent Sertoli cells are joined by tight junctions located on their basolateral walls, forming the so-called blood-testicular barrier.
The spermatozoa remain in a basal compartment located below the barrier.
During spermatogenesis, some cells resulting from sperm division pass through these junctions and occupy the adluminal compartment, which lies above the barrier.
The spermatocytes and spermatoids remain in the gaps in the lateral walls and apex of the Sertoli cells in the adluminal compartment, while the spermatoid flagella form tufts that extend into the lumen of the tubules.
The spermatozoa are probably released from the gaps by movements of the Sertoli cell apex, with the participation of microtubules and microfilaments.
In humans and other animals, Sertoli cells do not divide during an individual’s mature sexual life.
They are extremely resistant to adverse conditions such as infections, malnutrition and radiation and have a much better survival rate after these attacks, relative to cells of the spermatogenic lineage.
Sertoli Cell Functions
The functions performed by Sertoli cells are diverse. Between them, they help in the exchange of nutrients and metabolites of spermatocytes, spermatoids and spermatozoa.
The barrier formed by the Sertoli cells also protects the developing sperm from immune attack. Another function performed by the cells in question is the phagocytosis of excess cytoplasmic fragments released during spermiogenesis.
They also continually secrete fluid in the seminiferous tubules that is carried into the genital ducts and used to transport sperm.
Secretion of an androgen-binding protein by Sertoli cells is controlled by follicle-stimulating hormone and testosterone and serves to concentrate testosterone in the seminiferous tubules, where it is required for spermatogenesis.
Sertoli cells can convert testosterone to estradiol and also secrete a peptide called inhibin, which suppresses the synthesis and release of FSH by the pituitary.
This cell also produces anti-Müllerian hormone, which is a glycoprotein that acts during embryonic development to cause regression of the Müllerian ducts in male fetuses, thereby inducing the development of Wolffian duct-derived structures.
Finally, the tight junctions between the Sertoli cells form a barrier to the passage of large molecules through the space between them, thus protecting the more advanced stages of spermatogenesis, blood substances, and noxious agents.