The Sperm and Egg
Testes are suspended outside the abdominal cavity by the scrotum, a pouch of skin that keeps the testes close or far from the body at an optimal temperature for sperm development. Somniferous tubules are inside each testis, and are where sperm are produced by meiosis. About 250 meters (850 feet) of tubules are packed into each testis. Spermatocytes inside the tubules divide by meiosis to produce spermatids that in turn develop into mature sperm.
Sperm production takes place in the testes. The testes are in the scrotum. The scrotum is a sac located outside of the male's body. Since sperm can develop only in an environment with a temperature that is about 3°C lower than normal body temperature, the exterior position of the scrotum provides an ideal location.
Located within each testis, a fine network of highly coiled tubes are the production facilities for sperm. Sperm are produced through the meiosis of cells lining these tubes. Meiosis produces haploid cells. One cell divides by meiosis and produce four cells that mature into sperm. In human males, the production of mature sperm takes about 74 days. A sexually mature male can produce about 300 million sperm per day, each of his life. A sperm is highly adapted for reaching and penetrating the female egg. It can live for about 48 hours inside the female reproductive tract. A sperm is composed of a head, a midpiece, and a tail. The head contains the nuclear material and is covered by a cap containing enzymes that facilitate penetration of the egg. A number of mitochondria are found in the midpiece; they provide energy for locomotion. The tail is a typical flagellum that propels the sperm along its way.
Before the sperm mature, they move out of the testes through a series of coiled ducts that empty into a single tube called the epididymis. The epididymis is a coiled tube within the scrotum in which the sperm complete their maturation. Mature sperm...
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