Sertoli cells

Function

A Sertoli cell is a kind of cell, that secretes chemical substances necessary for the development and management of germ cells, resulting in the sperm cell production. It also blocks the interaction of blood with germ cells to prevent any damages done by the body immunity to its own germ cells and contrariwise it prevents the germ cells to provoke an immunological reaction in its own body.

One of the main parts of a testicle is the seminiferous (germinal) epithelium of seminiferous tubules responsible for the sperm cells production. There can be found very specific type of cells with utmost importance for development of sperm cells at different stages, called Sertoli cells. Sertoli cells have fundamental importance to the development and maintenance of spermatogenesis. There is a proportional numerical relationship of Sertoli cells to the sperm cell production. Sertoli cells secrete signalling molecules that promote sperm production and can control whether germ cells (“young” sperm cell stages) live or die. Sertoli cells take elongate form branching all stages of developing sperm cells, they physically extend themselves around the germ cells. 

Other function of Sertoli cells

Sertoli cells do not only control the process of spermatogenesis, but they are also responsible for creating so called immunologically privileged area in the testicles. It means, that Sertoli cell manage to keep blood separated from seminiferous tubules through the connection between them, called tight junction. Tight junction keeps bloodborne substances from reaching germ cells, so all stages of germ cells are protected from the body immunity. Tight junction also keeps surface antigens found on developing germ cells from eluding into the bloodstream so no autoimmune reaction could happen. Since Sertoli cells form the block between the blood and lumen of seminiferous epithelium, they are also in control of the entry and exit of nutrients, hormones and other chemicals into the tubules of the testis.

Secretory function of Sertoli cells

Following substances are secreted by Sertoli cells to manage the sperm production:

1. Anti-Müllerian hormone (AMH)

• secreted during the early stages of fetal life, necessary for development of male gonads

2. Inhibin and activins 

• secreted after puberty, and work together to regulate FSH secretion

3. Androgen binding protein (also called testosterone binding globulin) 

• increases testosterone concentration in the seminiferous tubules to stimulate spermatogenesis 

4. Estradiol 

• converts testosterone to 17 beta estradiol to direct spermatogenesis

5. Transferrin

• a blood plasma protein for iron ion delivery 

Development

Sertoli cells are required for male sexual development. Once fully differentiated, the Sertoli cell is unable to proliferate. Therefore, once spermatogenesis has begun (during puberty), no more Sertoli cells are created. Recently however, some scientists have found a way to grow these cells outside of the body. This gives rise to the possibility of repairing some defects that cause male infertility.

Management of Sertoli cells

Sertoli cells itself need an activation signal to start working properly. The triggering hormone activating Sertoli cells is called follicle stimulating hormone (FSH). FSH belongs to the group of hormones called gonadotropins, by the name it is clear, that the purpose of this group of hormones is to stimulate the function of gonads. In a male organism this hormone influences the sperm cell production through Sertoli cells.

Reproduction disorders related to Sertoli cells

1. Sertoli cell-only syndrome

• also known as Del Castillo syndrome and germ cell aplasia
• defined by the complete absence of germ cells in testicular tissues and always results in male infertility
• a disorder characterized by male sterility without sexual abnormality

2.Sertoli cell tumour

• Sertoli cells tumour normally occur only in the testis, but it may also rarely occur in the ovary of females