Sperm mystery solved

Scientists have solved a 20-year mystery regarding the molecular mechanism by which human sperm detect an egg. The answer lies in a unique ion channel that senses progesterone, causing an influx of calcium into the sperm cells. The finding, published in a pair of papers this week in linkurl:Nature,;http://www.nature.com/nature provides a clue to some types of male infertility, and could someday be the foundation for a non-hormonal contraceptive.

Illustration by linkurl:Carin Cain;http://www.carincain.com/home/

"It's a real step forward," said linkurl:Steve Publicover,;http://biosciences-people.bham.ac.uk/About/staff_profiles_contact.asp?ID=45 who studies human sperm at the University of Birmingham in the UK and was not involved in the research. "It gives us a handle on what is going on in sperm." Prior to fertilization, a cloud of cumulus cells surrounding the egg release progesterone, the female sex hormone, triggering a calcium influx into the sperm. This flood of calcium causes the sperm to beat their flagella rapidly, an...