BSIP VEM / SCIENCE PHOTO LIBRARY BSIP VEM / SCIENCE PHOTO LIBRARY
Sperm. Computer artwork of a single human sperm (spermatozoa). These tiny male sex cells are produced in the testes, and are responsible for fertilisation of the ovum (egg) of the female. The sperm has a rounded head (lower left) which contains the male hereditary material (DNA) and a long, whip-like tail that propels it along. Sperm production commences at puberty and is dependent on the male sex hormone testosterone. Some 300 million sperm are released by the male during ejaculation, while the human female usually produces one large egg. The sperm travel through the uterus and up the fallopian tubes to reach the egg. Only one sperm can fertilise the egg.
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