Sperm development (spermatogenesis) takes place in the testicles of males, where its development first becomes completed at the beginning of puberty.
The whole process takes approximately 70 days. Being a complex process, it is important to understand the regulating hormones and the testicular anatomy.
The male testes consist of two different compartments:
- The tubular compartment. It contains seminal canaliculi (small channels or ducts), which are lined by germinal epithelium. This compartment coordinates gametes and supporting cells, which nourish gametes and support their development.
- The interstitial compartment. This contains ‘Leydig cells’, which produce testosterone.
Sperm development is controlled by a number of hormones
The hypothalamus is part of the diencephalon (interbrain), and regulates sexual behaviour. Therefore, a great number of hormones are distributed, of which Gonadotropin-Releasing-Hormone (GnRH) influences the production of LH and FSH, which are vital for spermatogenesis.
The luteinizing hormone (LH) is produced by the hypophysis (pituitary gland) and stimulates the testosterone production in specific testicular interstitial cells (Leydig cells). The follicle stimulating hormone (FSH) is produced by the pituitary gland as well and has a direct effect on the germinal epithelium. Furthermore, testosterone and FSH influence testicular supporting cells, which coordinate spermatogenesis.
As soon as the development of the sperm cell is completed, it is being transported to the epididymis via the testicular canaliculi.
The epididymis consists of one single coiled duct, which is approx. 5 m long. The sperm cells are guided alongside and accomplish maturation on the way. This process is influenced by certain solutes and substances, distributed by the epididymis.
During the epididymal passage, which takes 2 – 10 days, the sperm cells gain both the ability of autonomous movement and the capability of binding to the oocyte. The sperm cells rest in the epididymis until the moment of ejaculation. As a result, there are spermatozoa – mature and fully functional sperm cells.