In a study appearing in the 28 March issue of the journal, Science, German and U.S. researchers report that the binding of certain compounds to the new odorant receptor (hOR17-4) found on the surface of sperm cells, triggers a series of physiological events that may result in the directed movement of human sperm. In this chemosensory response, the sperm cells travel toward elevated concentrations of a sperm-attracting substance called "bourgeonal."
"We were not expecting to uncover a receptor for chemo-attraction, this is the best we could expect to find," said author Marc Spehr of Ruhr-Universitt Bochum in Bochum, Germany, who noted that one of the next steps is to identify a female-produced equivalent to bourgeonal.
The scientists do not yet know if the egg itself produces some sperm-attracting compound similar to bourgeonal or if some other part of the female reproductive tract makes the chemical that may bind to the new receptor.
"If a natural equivalent to bourgeonal is, at least in part, responsible for successful pathfinding or screening of fertile sperm, then it should be possible to use bourgeonal within in-vitro fertilization (IVF) treatments," said Spehr. Success rates for IVF treatment are not as high as sterile couples and medical doctors would like, he added: "Some of the difficulties experienced in IVF treatments may be linked to the 'quality' of sperm. Bourgeonal might be used in the future to find the motile and fast sperm cells that are needed for fertilization." Further research is necessary before such approaches may be realized.
The researchers also identified an antagonist compound, "undecanal" that appears
Contact: Lisa Onaga
American Association for the Advancement of Science