When Dr. Petr Denissenko of the University of Warwick first saw sperm cells crashing as they negotiated the tight turns of channels en route to a woman's egg, he couldn't help but chuckle.
"I couldn't resist a laugh the first time I saw sperm cells persistently swerving on tight turns and crashing head-on into the opposite wall of a microchannel," he said.
Joking aside (Jezebel says, "Nothing more hilarious than a sperm that won't stop and ask for directions…," and The Daily Mail calls it an "appalling sense of direction"), a new study could help develop more effective treatments for infertility.
Despite so many images of sperm swimming like fish, researchers found that sperm rarely swim in the central part of the female reproductive tract. Instead, they avoid the "middle lane" and crawl along the sides of the walls.
Dr. Jackson Kirkman-Brown of the University of Birmingham says the study, published in the Proceedings of the National Academy of Sciences, could help answer two key questions in fertility treatment: How are the millions of sperm whittled down to around 10 that reach the egg, and can we use a similar method to select sperm for fertility treatments?
"In basic terms — how do we find the 'Usain Bolt' among the millions of sperm in an ejaculate?" he asked. "Through research like this, we are learning how the good sperm navigate by sending them through mini-mazes."
To conduct the study, cells were injected into hair-thin microchannels.
"Previous research from the group indicates that the shape of the sperm head can subtly affect how the sperm swim," Kirkman-Brown said.
"Combined with this data, we believe new methods of selecting sperm … may become possible."