Sperm cells are excellent swimmers

While we know that sperm cells can 'smell' chemicals given off by the egg once they get very close to it, this does not explain how they navigate for the majority of their journey, said Dr Jorn Dunkel of MIT, who conducted the research while a postdoctoral researcher at the University of Cambridge. "If you think of salmon for example, they can swim against the stream, and the question was whether something similar could really be confirmed for human sperm cells," said Dunkel.