Maths formula offers key to sperm fertility

The rhythm with which individual sperm move could explain why some successfully fertilise the female egg and others fail, a new Oxford University collaboration has found. From studying the rhythmic movements, researchers at the Universities of York, Birmingham, Oxford and Kyoto University, Japan, have developed a mathematical formula which makes it easier to understand how sperm make the journey to fertilise an egg. This knowledge will help scientists to gauge why some sperm are successful in fertilisation and others are not, potentially helping to treat male infertility. During intercourse, more than 50 million sperm set out to fertilise an egg, but only 10 make it to the final destination, before a single sperm wins the race and makes contact. The journey involved is treacherous and little known, and key to improving fertility treatment. The findings, newly published in the journal Physical Review Letters, showed that a sperm's tail has a characteristic rhythm that pushes the sperm forward, but also pulls the head backwards and sideways in a coordinated fashion. These actions move the fluid in a way that can be captured to form a relatively simple mathematical formula.