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Sexual reproduction allows some of the genetic information from each parent to mix, producing offspring that resemble their parents, but are not identical to them. In this way, sexual reproduction leads to variety in the offspring. Animals and plants can reproduce using sexual reproduction.

In sexual reproduction new organisms are produced from the fusion of a male sex cell with a female sex cell. This fusion of gametes is called fertilisation.

Sex cells are also known as gametes. Male gametes are made by male reproductive structures. Female gametes are made by female reproductive structures.

Male reproductive structures

Male gametes are called sperm cells. They are continuously produced in the testes.

During sexual intercourse sperm cells travel through the sperm duct, into the urethra and are released out of the end of the penis.

Female gametes are called egg cells and are produced in the ovaries of the female mammal.

In human beings, each gamete contains 23 chromosomes, half the number found in the other cells of the body. When the male and female gametes fuse, they become a zygote containing the full 46 chromosomes, half of which came from the father and half from the mother.

The zygote divides to form two new cells, which then continue to divide many times. Many of the new cells produced become specialised to perform particular functions and form all the body tissues of the new individual.