Related topics: eggs · fertilizer · genes · infertility · females

Females supercharge sperm evolution in animals

Sperm size varies dramatically among different animal species. But why is sperm size so variable when they share the same job—to fertilize eggs? In a new article published in Nature Ecology and Evolution, researchers from ...

Hope for infertile men: Mice could hold the secret

Male infertility affects more than 20 million men globally and is a contributing cause to around 50% of infertility in couples. Frequently, male infertility is the result of defects in the sperm tail, the flagellum, which ...

A new clue to killer whale cluster behavior

A Flinders University researcher has finally fathomed why large numbers of killer whales gather at a single main location off the Western Australian southern coastline every summer.

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Sperm

The term sperm is derived from the Greek word (σπέρμα) sperma (meaning "seed") and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell. The human sperm cell is haploid, so that its 23 chromosomes can join the 23 chromosomes of the female egg to form a diploid cell. A uniflagellar sperm cell that is motile is referred to as a spermatozoon, whereas a non-motile sperm cell is referred to as a spermatium. Sperm cells cannot divide and have a limited life span, but after fusion with egg cells during fertilization, a totipotent zygote is formed with the potential to develop into a new organism.

The spermatozoa of animals are produced through spermatogenesis inside the male gonads (testicles) via meiotic division. They are carried out of the male body in a fluid known as semen. Mammalian sperm cells can live for up to 3 days inside the female reproductive system.[citation needed]

Sperm cells in algal and many plant gametophytes are produced in male gametangia (antheridia) via mitotic division. In flowering plants, sperm nuclei are produced inside pollen.

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