A popular fertility treatment introduced in the early 1990s has been linked to low sperm counts in men born from the procedure. Scientists aren't entirely sure why this is happening, but it's entirely possible that fathers are passing their fertility issues down to the next generation.
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In preparation for the upcoming Olympics in Brazil, a British long jump champion is planning to freeze his sperm just in case he contracts Zika. It's meant as a precaution to prevent any future children from developing birth defects, but in reality it's a complete overreaction based on unfounded fears.
Fruit flies have enormous sperm. This is a well known fact in the scientific community — so well known, in fact, that there's a name for it: the big sperm paradox. But the massive, spermy problem has long confounded scientists, who couldn't figure out why such a tiny creature needed such humongous baby batter soldiers. Until now.
You know the story of mammalian fertilisation: millions of sperm enter the vagina, only one fertilises the egg, more than one messes up the embryo, yadda yadda yadda. Turns out that's not the only way it can work.
Ejaculation may feel like a glorious mess, as uncontrollable as an avalanche or a runaway train. In reality, it's a tightly choreographed court dance: integrating three different branches of the nervous system, triggering cascades of contractions in smooth and striated muscles, all accompanied by the electrical storm of orgasm. Here's how it works.
As sperm swim they transform chemical energy into motion, the way a car's engine uses gas to propel you down the road. Like that engine, the process is complicated — if just one part stops working, the whole system can grind to a halt. This idea might lead to a contraceptive for men that's reversible.