Internal Male Reproductive Organs

The internal male reproductive organs consist of the epididymis, vas deferens, seminal vesicles, prostate gland, ejaculatory ducts, and urethra. (See Figure 3.1.)

Epididymis

The epididymis is a long, thin, hollow coiled tubular system within the scrotum. A man has two epididymides; each one sits on top of its corresponding testicle. Sperm that are still maturing leave the testicle, enter one end of the epididymis, and loop and coil along the path. The sperm's journey takes about 10 days, and by the end of this course, the sperm are completely mature. The tail end of the epididymis acts as a sort of holding and storage tank for the mature sperm. It is connected to a straighter, thicker tube called the vas deferens.

Figure 3.1. Male Reproductive System

Right kidney

Sacrum

Figure 3.1. Male Reproductive System

Right kidney

Sacrum

Anus

Bulb of penis

Sagittal View

Anterior View

Illustration copyright © Nucleus Medical Art, all rights reserved, nucleusinc.com.

Anus

Bulb of penis

Sagittal View

Anterior View

Illustration copyright © Nucleus Medical Art, all rights reserved, nucleusinc.com.

Vas Deferentia

The vas deferentia consist of two tubes that serve as sperm ducts. The vas deferentia actually look a lot like strands of spaghetti, but they serve as the pipes and plumbing works for sperm. They transport the mature sperm from the epididymis and into the pelvic cavity. Once inside the pelvic cavity, the vas deferentia pass over the bladder and eventually connects with the seminal vesicles to form the ejaculatory ducts. Just prior to ejaculation, the sperm are mixed with the seminal fluid. The seminal fluid is composed of secretions from the seminal vesicles and the prostate gland.

Seminal Vesicles

Seminal vesicles are two small glands located just behind the bladder. Their purpose is to secrete a thick liquid that accounts for about 30 percent of the semen fluid volume.

Prostate Gland

The prostate gland is a walnut-sized gland located below the bladder. It contributes the majority of the secretions to the seminal fluid. The prostate's secretions are opaque white and give the semen its characteristic milky white color.

Ejaculatory Ducts

The ejaculatory ducts are two short tubes that descend through the prostate and into the urethra. They are formed by the union of the vas deferens, the seminal vesicles, and an opening within the prostate. It is here that the three components of semen are combined together. The thick liquid from the seminal vesicles, the milky fluid from the prostate, and the sperm from the vas deferens all combine here to make semen. Semen is 98 percent seminal fluid and 2 percent sperm. It will eventually be ejaculated from the penis. (If ejaculation does not occur, then the sperm will merely be absorbed by the body.)

Urethra

The urethra is the major transporting tube for both urine and semen. The urethra originates in the bladder, and it also runs down through the prostate gland. It ends at the opening slit at the end of the penis. The urethra possesses an elaborate mechanism of muscles to alternatively block the passageways of urine or semen. This ensures that both urine and semen can travel through the urethra, but never at the same time.

0 0

Post a comment