Crafty Sperm: Researchers have discovered that human sperm cells use scent to find an egg:

German researchers trying to work out how sperm find their way to their intended destination have identified an odour receptor in testicular tissue, usually found in the sensory nerve cells of the nose.

In laboratory tests, the receptor kick-started a process where sperm were drawn towards concentrations of an artificial scent called bourgeonal, which triggers the receptor in nasal cells.

The results have implications for infertility treatment as well as the development of non-hormonal contraceptives.