Sperm
hideThe 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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News tagged with sperm
Stem cells battle for space
Dec 04, 2009 |
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The body is a battle zone. Cells constantly compete with one another for space and dominance. Though the manner in which some cells win this competition is well known to be the survival of the fittest, how stem cells duke ...
'The pill' for him: Scientists find a hormonal on-and-off switch for male fertility
Nov 30, 2009 |
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A new research report published in the December 2009 print issue of The FASEB Journal could one day give men similar type of control over their fertility that women have had since the 1960s. That's because scientists have f ...
Hope for men with nonobstructive infertility
Dec 03, 2009 |
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It has been thought that men with non-obstructive azoospermia (NOA), a lack of sperm in the semen not caused by an obstruction within the reproductive system, are poor candidates for IVF. Now, researchers writing in the open ...
Newly discovered mechanism allows cells to change state
Dec 09, 2009 |
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Cells are not static. They can transform themselves over time — but change can have dangerous implications. Benign cells, for example, can suddenly change into cancerous ones.
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Ovaries must suppress their inner male
Dec 10, 2009 |
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For an ovary to remain an ovary, the female organ has to continuously suppress its inner capacity to become male. That's the conclusion of a study in the December 11th issue of the journal Cell revealing that t ...
Understanding DNA Repair and Cancer
Dec 03, 2009 |
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(PhysOrg.com) -- A protein that plays a key role in copying DNA also plays a vital role in repairing breaks in it, UC Davis scientists have found. The work is helping researchers understand how cancer cells can resist radiation ...
Why females live longer than males: is it due to the father's sperm?
Dec 01, 2009 |
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Researchers in Japan have found that female mice produced by using genetic material from two mothers but no father live significantly longer than mice with the normal mix of maternal and paternal genes. Their findings provide ...
Opposites attract: Monkeys choose mating partners with different genes
Nov 24, 2009 |
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The world's largest species of monkey 'chooses' mates with genes that are different from their own to guarantee healthy and strong offspring, according to a new research study.
Mexican labs target adulterers with DNA testing
Nov 20, 2009 |
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Suspect your significant other might be cheating on you? In Mexico, numerous laboratories are now offering a way to find out for sure -- DNA tests.
Modern Turkey: Modern Miracle
Nov 18, 2009 |
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(PhysOrg.com) -- Many of us will sit down with our families to a wonderful turkey dinner this Thanksgiving. But statistics increasingly show that Americans consider turkey a year-round staple.
Scientists Unravel Evolution of Highly Toxic Box Jellyfish
Nov 18, 2009 |
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(PhysOrg.com) -- With thousands of stinging cells that can emit deadly venom from tentacles that can reach ten feet in length, the 50 or so species of box jellyfish have long been of interest to scientists ...
Investigating muscle repair, scientists follow their noses
Nov 16, 2009 |
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When muscle cells need repair, they use odor-detecting tools found in the nose to start the process, researchers have discovered.
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