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.…
Researchers just found an on-off switch for sperm movement. This has the potential to help men who are infertile, but it also has the potential to help all men. It could be an effective form of male birth control.
Scientists from China have made history by taking a cell that’s not a sperm cell and then used it to create a live animal. A similar technique could be used one day to treat infertility in humans.
What you’re seeing in this video is obviously a sperm cell, except it was made in a lab, not a testicle. It’s designed to show how passive elastic swimming can mimic, fairly well, the motions that allow sperm (or fish) to swim.
A mouse’s sperm is much, much larger than an elephant’s sperm. A fruit fly produces the longest sperm known to science. Why do tiny animals make big swimmers, but large animals make small ones?
Sperm usually swim in a 3D shimmy: a spiral wave travels down the whippy flagellum and rotates its head in a circle around its long axis. That “bulk swimming” is fine most of the time, but it isn’t a great option when a sperm cell gets close to a surface. That’s when they switch to “slither” mode.
For the past 25 years, men whose sperm can’t manage the arduous swim across a Petri dish have had the option of injecting a single sperm cell directly into an egg. But that method still left some sterile men out in the cold.
You know the story of mammalian fertilization: millions of sperm enter the vagina, only one fertilizes the egg, more than one messes up the embryo, yadda yadda yadda. Turns out that’s not the only way it can work.
Farming emus means breeding emus. And Irek Malecki of the University of Western Australia thinks that the results could be improved with a bit of artificial insemination. But it’s easier said than done, as detailed in this amusing video.
Women know that menopause can put a “sell by” date on getting pregnant, but common wisdom says that men retain much of their fertility well into old age. That common wisdom is wrong.
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…
Two penguins at the Monterey Bay Aquarium decided to make baby penguins in front of their viewing window. In the process, they showed off a fascinating aspect of bird reproductive biology.
Get your weekend started right by watching how sperm sometimes form power-swimming blocks to get ahead. And learn why these particular sperm get together.
Biologists already knew that one set of neurons play a big role in triggering puberty. A new study shows that these neurons don’t stop working once puberty ends, but keep running through adulthood, serving as a sort of reproductive timer.
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.
Lots of human cells are specialized, but I can’t think of any that are as stripped down to a single purpose as spermatozoa. Sperm have just one job, and they’ll die doing it.
The successful union of egg and sperm in fertilization depends on a sperm cell’s ability to get through an egg’s thick protective coating and latch itself to its membrane. A study published in the journal Andrology yesterday gives us our first look at the protein responsible for the tie-down.
A sperm’s journey from vagina to egg is only 15 centimeters long, but it’s a race with attrition.
Doctors have long observed odd, circular cells in semen. They resemble undeveloped sperm, but scientists have been unable to work out how or why they appear—until now.
Human testes are masters of mass production, spitting out sperm at a rate of 200 million per day. But that doesn’t mean the process is fast–it takes 64 days to make a sperm. The organ keeps the count high with an assembly-line anatomy that scales up sperm development from a trickle to a flood.