Science glossary film: Fertilization

The fusion of two sex cells to create a new organism. Fertilization happens in different ways in different organisms, but always involves the fusion of an egg cell from a female with a sperm from a male, which leads to the development of an embryo. Mammals use internal fertilization, and fertilize only a small number of eggs. Plants and many marine creatures tend to use external fertilization, and may fertilize thousands or even millions of gametes at once.

Fertilization happens in different ways in different organisms, but always involves the fusion of an egg cell from a female with a sperm from a male, which leads to the development of an embryo. Mammals use internal fertilization, and fertilize only a small number of eggs. Plants and many marine creatures tend to use external fertilization, and may fertilize thousands or even millions of gametes at once.