Carin Cain

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 Nature, provides a clue to some types of male infertility, and could someday be the foundation for a non-hormonal contraceptive.