Penis Picture

The Testes

The male sexual glands, the two testes within the scrotum produce sperm and testosterone. Within each testis is a kilometer of ducts called the seminiferous tubules, the organs which generate sperm. Each testicle produces nearly 150 million sperm every 24 hours.

The Epididymis

After the sperm are produced with the seminiferous tubules, they enter the epididymis, a long, coiled tube that rests on the back side of each testis. The sperm stay in the epididymis until they are mature, a process that takes about 20 days. During sexual arousal, contractions of the epididymis force the sperm into the vas deferens. If ejaculation does not occur, sperm are simply reabsorbed into the body.

The Vas Deferens

The vas deferens is a long thin structure approximately 17 inches long that travels from the epididymis into the pelvic cavity to just behind the urinary bladder, where it enlarges into a region known as the ampulla. During ejaculation, sperm is expelled from the ampulla and into the ejaculatory duct, where it leaves the body. Besides receiving sperm, the ejaculatory duct also collects seminal fluid from the seminal vesicles.

When a man receives a vasectomy, it is the vas deferens that is surgically altered. A vasectomy renders the male sterile by blocking the passage of sperm into the pelvic cavity. The male still ejaculates, however his ejaculate does not contain any sperm. Sperm is still produced after vasectomy, but it cannot exit the body. Over time, the sperm are broken down and reabsorbed by the body.

The Seminal Vesicles

The seminal vesicles are small pouches that lie along the back side of the bladder. The seminal vesicles produce a sugar-rich sticky yellow fluid known as fructose, which provides the sperm with a source of energy, aiding in their motility and longevity. The fluid produced by these vesicles enters into the ejaculatory duct shortly after sperm are deposited into the duct. Seminal fluid is a major component of semen-it makes up approximately 60% of a man's ejaculatory fluid.

The Prostate Gland

The prostate gland is located in the male pelvis behind the pubic bone, in front of the rectum, and surrounded by the pelvic muscles. Usually the size of a walnut, the prostate varies in size and measures about 1-2 inches long by 2-3 inches wide. Growth and function of the prostate is regulated by testosterone and other male hormones. The main function of the prostate is to produce a large portion of the fluid vital to human reproduction. The prostate sits directly below the bladder; the urethra, which carries urine from the bladder to the penis, travels through the center of the gland. Sperm is produced in the testicles, then carried to the prostate, where it mixes with fluid produced by the prostate and seminal vesicles. During orgasm, the ejaculatory ducts eject this fluid, which is known as semen (and a host of other euphemisms).

The Bulbourethral Glands

The bulbourethral glands or Cowper's glands, are two small glands located on the sides of the urethra just inferior to the prostate gland. These glands produce a clear slippery fluid that empties directly into the urethra. Small amounts of this fluid may appear on the tip of the penis prior to ejaculation. This pre-ejaculatory fluid serves to lubricate the urethra as well as to neutralize it from any acidic conditions that might be present due to residual drops of urine. This fluid may also contain small amounts of sperm. Therefore, to ensure that your partner doesn't get pregnant, it's essential to take the same precautions as you would with ejaculation.