Male Sexual Anatomy

 

 

The Scrotum 

The scrotum is a thin loose sac of skin underneath the penis that is sparsely covered with pubic hair and contains the testicles [testes]. The scrotum has a layer of muscle fibers that contract involuntarily as a result of sexual stimulation, exercise, or exposure to cold, causing the testes to be   drawn up against the body. In hot weather, the scrotum relaxes and allows the testes to hang more freely away from the body. These reflexes of the    scrotum help to maintain a stable temperature in the testes, an important function because sperm production [occurring in the testes] is impaired by heat or cold. In response to cold, the scrotum lifts the testes closer to the body to provide the warmer environment. In hotter conditions, the scrotum loosens, thereby moving the testes away from the body and providing a larger skin surface for the dissipation of heat. Tightening of the scrotum with sexual arousal or physical exercise may a be protective reflex that lessens the risk of injury to the testes.  

  The Testes

  The testes (the male gonads) are paired structures usually contained in the scrotum. The testes are about equal size, averaging 5 x 2 x 3 centimeters in adults, although one testicle generally hangs lower than the other. Most often , the left testes is lower than right one, but in left handed men reverse is usually true. There is no significance attached to the relative height of the testes within the scrotal sac, but if one testis is considerably larger or smaller than the other rather could be a medical problem and a doctor should be seen.

The testes are highly sensitive to pressure or touch. Some men find that light caressing or stroking of the scrotum or genital squeezing of the testicals during sexual activity is arousing, but many others are uncomfortable with touching in this region.

The testes have two separate functions: hormone and sperm production. The cells that manufacture hormones – most importantly, testosterone, which controls male sexual development and plays an important part in sexual interest and function – are called Leydig’s cells. Sperm production occurs in the seminiferous tubules, tightly coiled tubes of microscopic size that collectively measure almost 500 meters ( more than a quarter mile 0 in length. The entire process of sperm production takes seventy days. Unlike the female , who creates no new eggs after birth, the male produces sperm from puberty on, manufacturing billions ns of sperm annually.

A mature sperm is considerably smaller than the size of a human egg, being about 0.06 millimeter  in length and thousands of times smaller than the egg in volume. Sperm are only visible with the aid of a microscope, which shows that they consist of three pieces: a head , a midpiece, and a tail. The chemical reservoir ( the acrosome). The mid piece contains an energy system that allows the sperm to swim by lashing its long tail back and forth.

The Epididymis and Vas Deferns

The seminiferous  tubules ( the tubes where sperm are produced ) empty into the epididymis, a highly coiled tubing network folded against the back surface of each testis . Sperm cells generally spend several weeks traveling  slowly through the epididymis as they reach full maturation. From here sperm are carried into the vas defens, a long tube (approximately 40 centimeters) a pair of which  leave the scrotum and curve alongside and behind the bladder. Both the right and left vas defens are cut when a vasectomy is done.