This change in behavior, called hyperactivation, enables the sperm to sweep the area once in the egg’s proximity, which improves the sperm’s chances of finding it.
For the in vitro study, the researchers designed microfluidic chips with micron-sized channels so they could observe bovine sperm with a microscope and a high-speed camera.
By exposing the mechanisms involved, the study not only unravels a mystery of how the sperm navigates to the egg, but it also has implications for human in-vitro fertilization and dairy cow reproduction and provides new information for engineers to design robotic micro swimmers.
“By understanding what determines the navigational mechanism and the biophysical and biochemical cues for a sperm to get to the egg, we may be able to use those cues to treat couples with infertility issues and select the best strategy for in vitro fertilization,” said Alireza Abbaspourrad, the paper’s senior author and the Youngkeun Joh Assistant Professor of Food Chemistry and Ingredient Technology in the Department of Food Science in the College of Agriculture and Life Sciences.
The study, “Mammalian Sperm Hyperactivation Regulates Navigation Via Physical Boundaries and promotes Pseudo-Chemotaxis,” was published online Oct. 29 in the Proceedings of the National Academy of Sciences.