The male reproductive system consists of three main components:
The testicles (also called testes) are part of the male reproductive system. The testicles are two oval organs about the size of large olives. They are located inside the scrotum, the loose sac of skin that hangs behind the penis. The testicles make the male hormones, including testosterone, and produce sperm, the male reproductive cells. Disorders of the testes can lead to serious complications, including hormonal imbalances, sexual dysfunction and infertility.
The epididymis is a long, narrow tube, which is coiled and contained beneath a fibrous sheath. Uncoiled, the epididymis would be approximately nineteen feet in length. The epididymis sits on the back of the testis, and it is divided into head, body and tail regions. Here sperm undergo their final development and maturation, and are stored until they are made available for ejaculation. From the epididymis, sperm proceed into the vas deferens, also known as the spermatic cord.
The vas deferens is a narrow, muscular tube that connects the testicles (where sperm is produced) to the urethra. During ejaculation, the sperm flows out of the testicles, through the vas deferens, and into the tube (urethra) that leads outside the body through the penis.
Several glands, such as the prostate gland, add fluid to the sperm along the way.
Normal male reproductive physiology
The production of sperm is a very complicated process that begins at puberty and lasts, in healthy males, until death. The production of sperm begins in the testicles and is controlled by several hormones. These hormones are regulated by the hypothalamus and the pituitary gland located in the brain.
The hypothalamus regulates the hormonal activity of the pituitary gland by secreting gonadotropin-releasing hormone (GnRH). This hormone controls the production of the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), from the pituitary. LH triggers the production of testosterone (a hormone needed for sperm production). FSH also triggers hormones that help with sperm production.
From beginning to end, sperm production takes about 72 days. Sperm spend their first 50 days in the testicles and the last 22 to 24 days in the epididymis. It is in the epididymis that sperm mature and gain motility (the ability to swim). During sexual activity, motile sperm are ejaculated into the female reproductive tract and begin their journey through the cervix and uterus to the fallopian tubes, the site of fertilization. There are many pockets (crypts), folds or ‘wrong turns’ along the way that can prevent many of the sperm from reaching their final destination. This is why so many sperm are needed for the fertilization process.
Over 15% of couples experience difficulty in conceiving a child after attempting for one year. Although in the past infertility problems were attributed to the woman, we now know that a male factor plays a role in almost one half of cases.
Causes of male infertility can be divided into two categories; physical abnormalities of the male reproductive tract, such as epididymal or vas obstruction or impaired sperm production and secondly, abnormalities of the sperm themselves. However in most cases of male infertility the cause is unknown.
To determine male fertility we carry out a semen analysis where we test the number, activity and shape of the sperm.