Although the terms are often confused or used interchangeably, sperm and semen are not the same thing. Semen is the fluid that comes out of the penis, while sperm are the microscopic cells within the semen. Sperm cells are specialized for the task of fertilizing an egg. Semen analysis is considered essential for diagnosis of male infertility, but is not readily available at medical institutions other than those specializing in infertility treatment. 'Fertility specialists take it for granted that the first step in diagnosing male infertility is to perform a semen analysis,' Professor Kobayashi added.

If you've got somebody that's had an egg collection, and you've got eggs that need to be fertilised, there's only a small time window for us to be able to do that. Speeding up the process would be hugely advantageous.

A 3D filming technique has revealed that human sperm really swim with a corkscrew motion like otters, rather than wiggling like eels due to their'wonky tails'. Developed by scientists led from Bristol, the method has overturned a 350-year-old belief that sperm tails lash'with a snakelike movement, like eels in water.' In fact, the researchers said, this is merely an optical illusion -- one that is a product of seeing the motion under standard, two-dimensional microscopes. Seen in three dimensions, the reproductive cells instead clearly rotate like a corkscrew as they strive to journey towards an egg. The findings could help to better understand and address the causes of male infertility -- which is thought affect around one-in-seven British couples. A 3D filming technique has revealed that human sperm (pictured in this artist's impression) swim with a corkscrew motion, rather than wiggling like eels due to their'wonky tails' 'With over half of infertility caused by male factors, understanding the human sperm tail is fundamental to developing future diagnostic tools to identify unhealthy sperm,' said paper author Hermes Gadelha of the University of Bristol.