A team of Dutch scientists used Magnetic resonance imaging of male and female genitals during coitus and female sexual arousal. The group also traced other experiments in this field of study, most notably, that of Leonardo Da Vinci, whose drawing "The Copulation" showed that semen in males comes from the brain and goes down the spine. Sort of gives you confirmation about how certain parts of the population think. Feh.
But really now, the Dutch, they really know how to do a really cool science project.