What are the parts of the male reproductive system?A man’s fertility and sexual characteristics depend on the normal functioning of the male reproductive system.
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What is the testis?The testes (testis, singular) are a pair of oval-shaped glands (each 15-35 ml in volume) that are suspended in the scrotum. The testes are the main male reproductive organ and are very important for the normal functioning of the male reproductive system. The testis is made up of two parts, with each part having a different but important role:
- Production of sperm
Sperm are made in the testes in a number of small, tightly packed, fine tubes called seminiferous tubules. These tubules have a total length of 150 metres. Sperm production is a continuous process with thousands of sperm being made each day after puberty.
 More information: Sperm Production
- Production of testosterone
Between the seminiferous tubules lie another cell type, Leydig cells, that produce the male sex hormone, testosterone. Testosterone, together with the hormone FSH, acts on the seminiferous tubules to ‘drive’ sperm production.
More information: Male Hormones
Before birth, the developing testes move down from the abdomen into the scrotum. Successful descent of the testes is important for fertility as a cooler temperature in the scrotum is needed for sperm production and normal testicular function. In humans, this location seems important because it keeps the testis 3 to 5 degrees below normal body temperature. Back to top
What is the epididymis?The epididymis is a highly coiled tube (duct) that lies at the back of the testes and connects the seminiferous tubules in the testis to another single tube called the vas deferens. The epididymis is about 5 metres long if stretched out. All sperm must pass through the epididymis when they leave the testis. When released from the testis, the sperm spend two to 10 days passing through the epididymis. During this journey, the sperm mature and gain the ability to move (swim or become motile). Back to top
What is the vas deferens?The vas deferens is the tube that connects the epididymis to the urinary tract (urethra) at the back of the bladder, via the ejaculatory duct. The main function of the vas deferens and ejaculatory duct is to transport the mature sperm and seminal fluid to the urethra. Back to top
What is the ejaculatory duct?The ejaculatory duct is a tube that is formed by the joining of the vas deferens and the duct of the seminal vesicle. The ejaculatory duct empties the mature sperm and seminal fluid into the urethra. Back to top
What is the urethra?The urethra is a tube that runs from the bladder to the end of the penis. It carries urine from the bladder to the outside of the body. In men, it also carries semen out of the body.
The urethra is made up of two parts. The prostatic urethra is the part of the urethra that runs from the bladder through the prostate. The penile urethra is the part of the urethra that runs through the penis.
A ring of muscle called the internal sphincter is located at the base of the bladder and when closed, it stops urine and semen leaving the body through the urethra at the same time. At orgasm, this muscle ring closes tightly to stop sperm passing ‘backwards’ into the bladder. Back to top
What is the prostate gland?The prostate is a small, but important organ (or gland) found only in the male reproductive system. Its main role is to make fluid that protects and feeds sperm. The prostate makes about half of the fluid ejaculated from the penis when orgasm happens.
In young men, the prostate is about the size of a walnut (20g) and gets bigger as men get older. It sits underneath the bladder and surrounds the top part of the urethra, the tube which urine passes through on its way from the bladder to the penis. The growth of the prostate relies on testosterone (male sex hormone). If the prostate grows too large, it can slow or stop the flow of urine. As the prostate is located near the rectum (back passage), growth of the prostate can be checked by a rectal examination where a doctor places a gloved finger into the rectum.
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What is the seminal vesicle?The seminal vesicles are two small glands that lie directly above the prostate gland, attached to the vas deferens near the base of the bladder. These glands are very active and make a fluid that makes up about half of the fluid volume of the semen. The fluid produced by the seminal vesicles is rich in fructose (a sugar) that may be important as an energy source for sperm. Back to top
What is the cowper's glands?The Cowper’s glands are pea sized glands that sit near the prostate gland in the male reproductive system. The glands produce a fluid that is released before ejaculation that neutralises any urine that may be left in the urethra. The fluid also acts as a lubricant. Back to top
What is the scrotum?The scrotum is a loose pouch of skin that hangs outside the body from the lower abdominal region behind the penis. The scrotum holds the testes in place. Back to top
What is the penis?The penis is the male organ used for urination and sexual intercourse. The penile urethra is the part of the urethra that passes through the penis. Back to top
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