Abstract
In mammals, spermatozoa complete meiosis before spermiation, while oocytes do not complete meiosis before ovulation. A mature spermatozoon weighs only picograms, and its head length is approximately 5 μm. On the other hand, a mature oocyte weighs 20–40 ng and is approximately 100 μm in width. Since spermatozoa have to cover a large distance to reach the oocyte, the sperm nucleus (containing the genome) must remain in a protected and safe condition; in fact, it is thoroughly embedded in the nuclear matrix. Approximately 2.5 × 107 of such structurally complex spermatozoa are produced daily in the human testes; in comparison, only a few oocytes (generally 1 cell per menstrual cycle in humans and about 10 per estrous cycle in rodents) develop in the ovaries and are ovulated into the fallopian tube.
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© 2009 Springer-Verlag Berlin Heidelberg
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Toshimori, K. (2009). Mammalian sperm head. In: Dynamics of the Mammalian Sperm Head. Advances in Anatomy, Embryology and Cell Biology, vol 204. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-89979-2_2
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DOI: https://doi.org/10.1007/978-3-540-89979-2_2
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Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-89978-5
Online ISBN: 978-3-540-89979-2
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