Male reproductive system

Sperm are the male reproductive cells.

Normal, mature sperm are highly specialised cells approximately 0.05 mm long with three main parts: head, neck and tail.

In the head is a structure called the nucleus, which contains 23 tightly packed chromosomes (the genetic material). The head of the sperm is designed to bind to and then enter (penetrate) the egg.

The neck joins the head to the tail. The part of the tail nearest the neck contains the mitochondria, which provides the energy for the sperm to move (motility).

The tail moves in a whipping motion to propel the sperm towards the egg.

See a video of sperm swimming: View in Media Player (4 Mb)

The male reproductive tract is made up of the testes, a system of ducts (tubes) and accessory glands opening into the ducts.

The testes contain a number of tightly coiled, fine tubes called seminiferous tubules. The cells in the lining of the seminiferous tubules divide over and over again to produce sperm.

The epididymis is a long, highly-coiled tube which connects the seminiferous tubules to another single tube called the vas deferens. The sperm spend two to 10 days passing through the epididymis. During this journey, the sperm mature and gain the ability to move. It takes about 70 days in total for sperm to develop into the mature sperm found in semen that can fertilise an egg.

The accessory glands aid in the maturation, nourishment and transport of the sperm through the male reproductive system and into the female’s body for fertilisation.

The ejaculate of fertile men contains tens of millions of sperm. However, men with much lower numbers of sperm can still achieve pregnancies. Men who never produce any sperm in their ejaculate cannot help a partner become pregnant without some form of treatment.