The Sertoli Cell – A Hormonal Target and ‘Super’ Nurse for Germ Cells That Determines Testicular Size

Abstract

The somatic Sertoli cell plays an essential role in embryonic determination of male somatic sex and in spermatogenesis during adult life. One individual Sertoli cell supplies a clone of developing germ cells with nutrients and growth factors and it is well established that the number of Sertoli cells present is closely correlated to both testicular size and sperm output. Sertoli cells continue to proliferate and differentiate until the beginning of puberty, when they cease dividing and start nursing the germ cells. At this point in time, the future capacity of the testis for sperm production has thus been determined. Prior to puberty the Sertoli cells are immature and differ considerably with respect to morphology and biochemical activity from the mature cell. The several investigations that have focused on hormonal and paracrine regulation of the functions of the mature cell are reviewed here, but the mechanisms underlying the maturation and general maintenance of well-functioning Sertoli cells remain obscure. An alarming decline in male reproductive health has been observed in several Western countries during recent decades. Disturbance of Sertoli cell differentiation is thought to be involved in the pathogenesis of both a poor sperm count and testicular cancer. It is speculated that environmental agents that disrupt the estrogenic/androgenic balance in the testis may play a role in this connection.

Microbiota and the control of blood-tissue barriers

“…At the same time, the BTB poses an obstacle to the development of non-hormonal male contraceptives by sequestering drugs (e.g., adjudin) in the apical compartment. 17 The BTB forms during puberty in human (at~12-14 years of age), while in mice a functional BTB is established~15-16 days after birth, 18,19 which coincides with the time-point at which the testis cords are transformed into seminiferous tubules with a lumen, 20,21 as well as when the Sertoli cells cease to divide and become terminally differentiated. 22 Thus, in adult mammals the number of Sertoli cells is thought to remain relatively constant, 19,22 although there are reports that these cells can proliferate and divide in adult rodents under experimental conditions 23 and even under physiological conditions in humans.…”

“…24 The number of Sertoli cells determines the number of germ cells that can be supported during spermatogenesis and thus sperm production and the sperm count in adulthood. 21,22 Sertoli cells are highly dynamic, changing their 3-dimensional structure during the course of spermatogenesis and spermiogenesis. 25,26 This causes the BTB to change as well: the TJPs undergo remodeling (opening and closing) to allow the passage of preleptotene spermatocytes from the basal to the adluminal compartment, where they undergo meiosis.…”

The insulin sensitiser metformin regulates chicken Sertoli and germ cell populations

“…Sertoli cells have a similar function to support, nourish, and protect germ cells, and are required for the appropriate differentiation of germ cells. The number of Sertoli cells will determine the number of germ cells and, therefore, the number of spermatozoa produced (de Reviers et al 1980, Petersen & Soder 2006. To carry out these functions correctly, it is necessary that Sertoli cells are sensitive to external signals such as systemic energy levels, hormones, and exogenous factors, and that they are able to transmit this information to germ cells through the modification of the secretion of factors crucial for spermatogenesis.…”

Protein prenylation and human diseases: a balance of protein farnesylation and geranylgeranylation

“…A physical barrier, the so-called blood-testis barrier (BTB), forms between Sertoli cells and allows for these cells to control and regulate the environment of the developing germ cells. More importantly, in addition to the BTB, Sertoli cells can secrete immunomodulatory factors that create an effectively immune-privileged environment [33,34].…”