Sperm Collide Along Liquid Maze on Way to Fertilize Egg
TUESDAY, May 8 -- Sperm cells navigate the complex fluid-filled channels of the female reproductive tract by crawling along walls and swimming around corners, a new study reveals.
And although millions of sperm cells are ejaculated, the few that actually reach an egg collide frequently along the way.
This new insight on how sperm travel could help scientists develop new treatments for infertile couples, say British researchers who injected the cells into hair-thin microchannels, or mini-mazes, to identify which sperm are the fastest swimmers and why.
"In basic terms, how do we find the 'Usain Bolt' among the millions of sperm in an ejaculate," study author Dr. Jackson Kirkman-Brown, lead in reproductive biology at the University of Birmingham and science lead at the Birmingham Women's Fertility Centre, said in a news release.
"Sperm cell following walls is one of those cases when a complicated physiological system obeys very simple mechanical rules," study leader Dr. Petr Denissenko, at the University of Warwick's School of Engineering, said in the news release.
As described by the researchers, the sperm's journey sounds more like a bumper car ride than a smooth swim upstream.
"When the channel turns sharply, cells leave the corner, continuing ahead until hitting the opposite wall of the channel, with a distribution of departure angles, the latter being modulated by fluid viscosity," the researchers said. "Specific wall shapes are able to preferentially direct motile cells."
The researchers concluded their findings could help scientists developing treatments for infertility to identify the strongest sperm cells.
The findings appear online in this week's issue of the Proceedings of the National Academy of Sciences.
The U.S. National Institutes of Health provides more information on infertility.
Posted: May 2012