Sperm-Egg Attraction Is Chemical, Study Finds

A study indicates that human sperm swim toward chemical attractants to find the female egg, a discovery researchers say could lead to new ways to treat infertility or create contraceptives that do not use hormones.

UCLA researchers report in the Friday issue of Science that human sperm have a receptor, or chemical sensor, that leads the sperm to swim toward concentrations of a chemical attractant. Biologist Richard K. Zimmer said the sperm were attracted to a compound called bourgeonal.

A compound in the human female reproductive tract that works like bourgeonal has not been found, but is widely believed to exist. Zimmer said the researchers also identified a compound, called undecanal, that shuts down the sperm receptor and keeps it from responding.

Zimmer said the discoveries could lead to drugs that could overcome some fertility problems or inhibit conception.

“The holy grail in reproductive biology has been to find the sperm attractant and to understand how it works,” said Dr. Donner F. Babcock, a researcher at the University of Washington in Seattle.