In the future, fertility treatments may include a "Sperm Olympics" event to select the ones that are not only the fastest, but able to slither like a snake!
Using a technique called total internal reflection fluorescence (TIRF) microscopy, a team of engineers from the University of Toronto was able to capture sperm movement within 100 nanometres of a flat surface. What they captured for the first time was that the sperm slithered in 2D from side to side like a snake. They observed this motion for about one sperm's body length before the sperm returned to the traditional 3D corkscrew motion.
How is this snake-like movement beneficial? The team observed that the 2D slithering improved the speed of the sperm by 50% in liquid conditions of higher viscosity. This could be a significant competitive advantage as the sperm travel through the female reproductive tract.
Previous work in microfluidics has shown that fast-moving sperm tended to have higher DNA integrity and are more likely to produce a viable embryo. Additional research has to be completed to show whether slithering is associated with similar positive advantages. But if it is, the sperm selection process for IVF treatments may soon have another "field event" that could include microchannels passable to only sperm that can slither. These combined traits could dramatically increase the odds of success for people undergoing IVF treatments.