Couples struggling to have children could have their chances boosted after a pioneering 3D filming technique revealed how sperm really swim for the first time.
The discovery by British scientists turns 350 years of science on its head which assumed their tail moved side to side “like a snake”.
It turns out this was an illusion created when the tiny tadpole-like organisms are viewed under a 2D microscope.
When shown in 3D sperm were shown to swim “like a spinning top” rotating only in one direction.
Lead author Dr Hermes Gadelha of Bristol University said: “Human sperm figured out if they roll as they swim, much like playful otters corkscrewing through water, their one-sided stoke would average itself out, and they would swim forwards.”
The best sperm are the ones that make it to fertilise the egg while more sluggish swimmers do not make it to procreate.
Identifying which are the best swimmers is crucial to selecting sperm for fertility treatments such as IVF, which have a high failure rate.
Our assumptions about this crucial technique were until now based on a discovery by Dutch scientist Antonie van Leeuwenhoek using one of the world’s earliest microscopes.
Dubbed “the father of microbiology”, he described sperm as having a “tail, which, when swimming, lashes with a snake-like movement, like eels in water”.
The swimming technique was only now identified using a 55,000 frames-a-second camera on a mechanism which moved the sample rapidly to photograph it from all angles.
Co-author Dr Alberto Darszon, of the Universidad Nacional Autonoma de Mexico, said: “This discovery will revolutionize our understanding of sperm motility and its impact on natural fertilization.
“So little is known about the intricate environment inside the female reproductive tract and how sperm swimming impinge on fertilization.
“These new tools open our eyes to the amazing capabilities sperm have.”
The ground-breaking study, published in the journal Science Advances, reveals the sperm tail is in fact wonky and only wiggles on one side.
Dr Gadelha added: “The sperms’ rapid and highly synchronised spinning causes an illusion when seen from above with 2D microscopes.
“Our discovery shows sperm have developed a swimming technique to compensate for their lop-sidedness and in doing so have ingeniously solved a mathematical puzzle at a microscopic scale, by creating symmetry out of asymmetry.
“With over half of infertility caused by male factors, understanding the human sperm tail is fundamental to developing future diagnostic tools to identify unhealthy sperm.”
