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Scientists Solve Mystery of Sperm Cell Swimming Stroke

Mommy, where do babies come from?

It’s a question no parent looks forward to hearing. While clever animalian metaphors and thinly-veiled innuendo might help hapless mothers and fathers explain the process of human reproduction to children, that child-like curiosity still fuels research into human reproduction and genetics. Despite centuries of medical knowledge, there still remain many aspects of conception and development that elude explanation. For one, scientists have for years attempted to understand how individual sperm are able to maintain their swimming direction towards eggs using their simple head-and-tail physical structure. Understanding this aspect of how sperm swim could lead to new types of infertility treatment and potentially help countless would-be parents, but so far the mechanism behind the swimming motion of sperm has remained a mystery.

As sperm swim, their heads whip backwards and sideways to generate movement.

As sperm swim, their heads whip backwards and sideways, suggesting that these cells are taking advantage of fluid dynamics in a quite sophisticated way.

Thankfully, a recent study into sperm movement has unlocked the curious swimming movements of these human reproductive cells. According to University of York mathematician Hermes Gadêlha, this research could shine light some of the unexplained aspects of human reproduction:

Around 55 million spermatozoa are found in a given sample, so it is understandably very difficult to model how they move simultaneously. We wanted to create a mathematical formula that would simplify how we address this problem and make it easier to predict how large numbers of sperm swim. This would help us understand why some sperm succeed and others fail.

To solve this mystery, researchers from the U.K.-based Universities of York, Birmingham, and Oxford and Japan’s Kyoto University filmed individual sperm cells as they swam using microscopic cameras that captured the cells’ movements at 300 frames per second. Those images were then analyzed by computers which were able to compute a mathematical algorithm that correctly predicts and models the whip-like motion of swimming sperm cells. 

The motion of individual sperm cells resemble the ways magnetic fields are formed around magnets.

The motion of individual sperm cells resemble the ways magnetic fields are formed around magnets.

According to the researchers’ data published in Physical Review Letters, the resulting mathematical formula can accurately predict the behavior of individual sperm cells and shows that they move in swirls similar to those seen in magnetic fields surrounding magnets. This breakthrough could potentially revolutionize male fertility treatments, possibly enabling fertility doctors to “guide” poor-swimming sperm in the right direction. If that doesn’t work, there’s always cannabis: research last year found that THC can actually improve sperm motility and sperm cells’ ability to initiate conception. Just watch out for the dreaded couch lock. That could definitely decrease your chances.