Sertoli Cells: Definition, Structure, Mode of Action and Related Diseases

In addition to their essential functions in the adult testicle, CS play a fundamental role during the development of the testicle.

In the adult testis, Sertoli cells (CS) are the supporting epithelial cells of the seminiferous tubules that provide the germ cells (CG) with the required nutrients and the structural and normative support to complete the spermatogenesis.

The CS also form the blood-testicle barrier, phagocytosis of apoptotic spermatocytes and cellular remnants derived from spermiogenesis, they also produce and secrete numerous paracrine and endocrine signals involved in different regulatory processes.

These cells can only proliferate in the first year of life (its equivalent in women are follicular cells).

It is activated with the follicle stimulating hormone (FSH) secreted by the anterior pituitary gland and has FSH receptor in its membranes.

Structure

Support cells (Sertoli) are found inside the seminiferous tubules.

These cells have abundant cytoplasm and extend from the basement membrane to the lumen.

The Sertoli cells have a characteristic oval nucleus with a dark nucleolus.

The cytoplasmic content and the blood testis barrier are best visualized under the electron microscope.

The Sertoli cells are shaped like a Christmas tree and sit on a basement membrane. Laterally they are in direct contact with each other and with the germ cells.

The Sertoli cell has an extensive cytoplasm and an oval-shaped nucleus that contains a prominent nucleolus and an extremely dense chromatin.

If you look closely, a large number of mitochondria and lipid drops are visible outside the nucleus, throughout the cytoplasm.

The basement membrane on which all Sertoli cells rest is visible, as is a narrow myofibroblasts that contract rhythmically.

The Sertoli cells are connected to each other with binding complexes near the basement membrane, these complexes divide the tubular epithelium into baseline and adluminal comparisons.

The basal compartment contains diploid spermatogonia, which rest on the basement membrane.

These cells develop upon migration to the adluminal compartment, which contains primary spermatocytes, spermatids and sperm.

The “firm union” as a barrier to the testes in the blood prevents the sperm from entering the bloodstream or into the lymphatic systems.

This is important because the immune system would produce antibodies against the antigens in the membrane of the monoploid sperm, which would lead to an autoimmune orchitis and, therefore, to sterility.

Action mode

Like all epithelial cells, Sertoli cells are avascular.

Sertoli cells are compatible with germ cell progenitors and help transfer nutrients from nearby capillaries.

Developing spermatogonia depends on Sertoli cells for all their feeding.

The blood-brain barrier formed by Sertoli cells effectively isolates spermatogonia, spermatocytes, spermatids and adult sperm from developing blood.

Differentiating sperm are nested in the pockets of the peripheral cytoplasm of these cells.

Sertoli cells also produce testicular fluid, including a protein that binds and concentrates testosterone , which is essential for the development of sperm.

They also help to translocate the differentiating cells to the lumen, and phagocytose the degenerative germ cells and remaining cytoplasm of the spermiogenesis.

It is important to note that the basal regions of the lateral borders of the Sertoli cells are connected to each other by continuous narrow junctions.

These divide the tubules into two separate compartments. The mitotic spermatogonia remain in the basal compartment.

The differentiating progeny enter the adluminal compartment and are sealed from the basal compartment.

If new antigens are expressed in haploid cells, then they are less likely to be detected by the immune system in this sealed compartment.

Related diseases

Germ cell aplasia:

Sertoli’s single cell syndrome (SCO), also called germ cell aplasia, describes a condition of the testicles in which only Sertoli cells line the seminiferous tubules.

In general, men with SCO syndrome appear between the ages of 20 and 40 for the evaluation of infertility and are found to be azoospermic, a term that describes the absence of sperm in the ejaculate.

There is no known treatment or effective medication to treat this condition.

Sertoli cell tumors:

Testicular Sertoli cell tumors are a very rare neoplasm with three identified subtypes: general, large cell calcification and sclerosing.

The TCSS are usually small (0.4-1.5 cm, 4 cm maximum), while the other subtypes can be significantly larger.

Histopathology shows a uniform pattern of tubules, cords and aggregates of Sertoli cells separated by extensive sclerotic stroma.

Extensive sclerosis is present in comparison with the focal sclerosis observed in general and the large cell calcifying Sertoli cell tumors.

Sertoli cell tumors stain positively for cytokeratin, an intermediate filamentous protein found in epithelial cells and tumors, in contrast to TCSS, which are negative for cytokeratin expression.

The Sertoli cell subtype, calcifying large cells, has been uniquely associated with precocious puberty, pituitary adenoma, suprarenocortical hyperplasia and cardiac myxoma.

An association between this subtype, tuberous sclerosis and Peutz-Jeghers syndrome has been described.

Such extratesticular manifestations have never been described in the sclerosing subtype, further supporting the clinical importance of the specific subtype assigned to Sertoli cell tumors.