Chasing Tails

Sperm need to generate a lot of power – the race to fertilise an egg whittles the competition down from 100,000 to one (or perhaps two). To assess the fittest swimmers, ‘sperm counts’ often look for bobbing heads (white) – to see how eager the cells are for this important swim. Here a new combination of techniques focusses on where the power for the journey ahead comes from – the tail. Each flagellum waves and beats to propel the sperm egg-wards, producing patterns with more subtleties than the sperm’s head movements. These two human sperm have their tail patterns tracked – with the sperm on the right ‘hyperactive’ after a chemical treatment. A mathematical model trained with these experiments can now predict tiny changes in forces and energy required for the sperm to travel effectively. Relating this to fertility may help with future treatments, or with selection of ‘healthy’ sperm for procedures like in vitro fertilisation.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image adapted from work by M T Gallagher and colleagues
• School of Mathematics Institute for Metabolism and Systems Research, University of Birmingham, Birmingham, UK
• Image originally published under a Creative Commons Licence (BY 4.0)
• Published in Human Reproduction, July 2019