Sertoli cell
Introduction
A Sertoli cell (a kind of sustentacular cell) is a 'nurse' cell of the testes which is part of a seminiferous tubule. Its main function is to nurture the developing germ cells through the stages of spermatogenesis. It was also called the "mother cell." The cell is also responsible for establishing and maintaining the spermatogonial stem cell niche, which ensures the renewal of stem cells and the differentiation of spermatogonia into mature germ cells that progress stepwise through the long process of spermatogenesis, ending in the release of spermatozoa.
Nomenclature
Sertoli cells are called so because of their eponym Enrico Sertoli, an Italian physiologist who discovered them while studying medicine in the University of Pavia, Italy. He published a description of this cell in 1865. The cell was discovered by Sertoli with a Belthle microscope purchased in 1862, which he used while studying medicine. In the 1865 publication, his first description used the terms "tree-like cell" or "stringy cell" and most importantly he refered to these "mother cells." It was other scientists who used Enrico's family name, Sertoli, to label these cell in publications, starting in 1888. As of 2006, two textbooks that are devoted specifically to the Sertoli cell have been published.
Functions
As mentioned earlier Sertoli cells are involved in the process of spermatogenesis. This process is stimulated by Follicle Stimulating Hormone (FSH) from the anterior pituitary gland.
Sertoli cells also secrete anti-Müllerian hormone (AMH) during the early stages of fetal life. After puberty, they secrete the hormone inhibin and activins.
The junctions of Sertoli cells form the blood-testis barrier, a structure that partitions the interstitial blood compartment of the testis from the adluminal compartment of the seminiferous tubules. Sertoli cells control the entry and exit of nutrients, hormones and other chemicals into the tubules of the testis as well as make the adluminal compartment an immune-privaleged site.
Once fully differentiated, the Sertoli cell is unable to proliferate. Therefore, once spermatogenesis has begun, 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.
They also secrete androgen binding hormone and glial cell line-derived neurotrophic factor (GDNF), which has been demonstrated to function in promoting undifferentiating spermatogonia, which ensures stem cell self-renewal during the perinatal period. Other factors, such as the Ets related molecule (ERM transcription factor) are needed for maintenance of the spermatogonial stem cell in the adult testis.