Using 3D microscopy, researchers found that the sperm’s tail doesn’t move from side to side, as previously thought, but rotates.
Researchers at the University of Bristol, England, and the Universidad Nacional Autonoma de Mexico made a revolutionary discovery in a new study: they found out how sperm actually “swim”. The study was published last week in the journal Science Advances.
More than 300 years ago, Dutch scientist Antonie van Leeuwenhoek used one of the first microscopes to describe the human sperm as having a “tail, which, when swimming, lashes with a snakelike movement, like eels in water.”
This description was believed to be correct, until now. According to the new study, this movement is just an optical illusion.
Using 3D microscopy, the team was able to observe how the tail of the sperm actually moves.
With a camera capable of recording more than 55,000 frames in a second, they were able to watch as the sperm swam freely.
They found that the sperm’s tail moves only on one side. Although this means that it should swim in circles, the sperm has found a clever way to adapt and swim forward: it spins, like an otter.
“The otter-like spinning of human sperm is however complex: the sperm head spins at the same time that the sperm tail rotates around the swimming direction. This is known in physics as precession, much like when the orbits of Earth and Mars precess around the sun,” said Dr. Hermes Gadelha from the University of Bristol, in a note.
This discovery may help in the search for treatments for fertility problems. “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,” Gadelha said.