Male reproductive system structure and function

The reproductive system of male is simpler compared to the female reproductive system as man does not nurture the product of conception.

It consists of a pair of tests situated in the scrotal sac, epididymis, vas deferens, seminal vesicles, ejaculatory ducts, prostate, bulbo-urethral glands and penis.

The two tests (singular=testis) develop inside the abdominal cavity and descend into the scrotum.

At birth both tests should be felt in the scrotum. Occasionally one or both testes can get pulled up especially when exposed to cold due to contraction of a muscle called cremaster.

This can be differentiated from undescended testes (a condition in which one or both testes fail to descend into the scrotum) by the fact that the testes can be brought down into the scrotum. Also in case of undescended tests the scrotal sac or that side (entire scrotum if both are undescended) is not fully developed.

Each testis is about one and a half inch long and one inch wide. It is made up of coiled tubes called seminiferous tubules. Each tubule is about 70 cm long and the total number of tubules is estimated to be more than 800.

The sperms develop inside the tubules. In between the seminiferous tubules are the cells of Leydig which secrete the male sex hormone-testosterone. Luteinizing hormone secreted by the Pituitary gland stimulates these cells to secrete testosterone.

The seminiferous tubules join together to form the epididymis. It is a tube about 20 feet long coiled on the back of the testis. The sperms mature in the epididymis.

The vas deferens is the continuation of the epididymis. It starts at the lower pole of the testis and enters the abdominal cavity through the inguinal canal. It joins the tube from the seminal vesicle of that side to form the ejaculatory duct which joins that part of the urethra which is inside the prostate.

The seminal vesicles are a pair of glandular structures situated behind the urinary bladder. They secrete a fluid which becomes part of the semen. It is rich in fructose which provides the energy for the sperms as they have to travel up the cervix and uterus to reach the ovum.

There are two ejaculatory ducts. Each is formed by the union of the vas deferens and the tube from the seminal vesicle. The two ejaculatory ducts open into the urethra.

The prostate gland secretes and stores a clear fluid which is slightly alkaline in nature. This fluid along with sperms and the fluid from the seminal vesicles constitute the semen. The alkalinity of semen neutralizes the acidity of the vagina and prolongs the life of sperms. The prostate gland also contains smooth muscles which help expel semen during ejaculation.

The bulbo-urethral glands (Cooper’s glands) are two in number situated below the prostate gland. Their ducts open directly into the urethra. The secretion from this known as pre-ejaculate lubricates the urethra for the passage of sperms.

The testes produce millions of sperms. Each milliliter of semen contains more than twenty million sperms. The sperms are produced by a process known as meosis-a type of cell division in which the number of chromosomes is reduced to half.

When a sperm unites with an ovum (which also has half the number of chromosomes) the resultant cell called zygote has exactly 23 pairs (46) chromosomes.

Sperms are of two types. A sperm containing an X chromosome is destined to give rise to a female fetus while a sperm containing a Y chromosome will give rise to a male fetus. All ova contain only X chromosomes.

Each sperm cell consists of a head and tail. The tail with its whipping movements helps to propel the sperm forwards to meet the ovum in the fallopian tube.

Though the semen contains millions of sperm, only one sperm can unite with one ovum. As soon as a sperm enters the ovum it becomes totally impervious to other sperm.

Return from male reproductive system to human body