sperm, also called spermatozoon, plural spermatozoa, male reproductive cell, produced by most animals. With the exception of nematode worms, decapods (e.g., crayfish), diplopods (e.g., millipedes), and mites, sperm are flagellated; that is, they have a whiplike tail. In higher vertebrates, especially mammals, sperm are produced in the testes. The sperm unites with (fertilizes) an ovum (egg) of the female to produce a new offspring. Mature sperm have two distinguishable parts, a head and a tail. The head of the sperm varies in shape for each animal species. In humans it is flattened and almond-shaped, four to five micrometres long and ...(100 of 795 words)

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