22.4: Male Reproductive System
- Page ID
- 53847
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The testes produce spermatozoa (sperm), the male reproductive cells. Spermatozoa are produced in the seminiferous tubules and collected by the rete testis (rete = net). Spermatozoa travels from the rete testis to the head of the epididymis where they mature and are stored until ejaculation. The vas deferens transports spermatozoa from the tail of the epididymis to the prostate gland. Seminal glands, the prostate gland, and the bulbourethral glands add fluid secretions to spermatozoa to form semen. These additional fluids support the spermatozoa and their survival as well as facilitate their transfer to the female reproductive tract.
Above: Male reproductive system, lateral view of the left side with structures shown with sagittal sections.
The epididymis, vas deferens, ejaculatory duct and urethra form a system of tubules for the transport of spermatozoa from testes to the pelvic cavity. There they will be combined with the secretions of the accessory glands to form semen.
Above: Structures of the male genitalia.
In order for proper and efficiently development of spermatozoa, the testes must be cooler than core body temperature (95°F is optimal for spermatogenesis and 98.6°F is core body temperature). The testes cool some just from being suspended away from the body, but the core temperature arterial blood from the gonadal artery must also be cooled before reaching the testis capillary beds. As blood is cooled in the peripheral capillary beds of the scrotal walls, it collects into a network of gonadal veins called the pampiniform plexus (pampiniform = shaped like a vine or tendril). As it ascends to the abdomen, this venous plexus wraps around the gonadal artery, cooling the arterial blood to sufficient temperature.
Above: Internal structure of the testis and epididymis.
Sperm cells are produced in the seminiferous tubules in the testes. A cross section through the process of spermatogenesis (a type of meiosis). Close examination of a cross section of a seminiferous tubule shows that sperm cells develop beginning close to the inner lining of the seminiferous tubule, beginning with specialized stem cells called spermatogonia, and develop as they move closer to the lumen of the seminiferous tubules. Primary spermatocytes (cells that undergo the first meiotic division) and secondary spermatocytes (cells that undergo the second meiotic division) are intermediate cells produced as spermatozoa develop. Spermatogenesis produces immature spermatids that ultimately mature into spermatozoa.