- Successful fertility relies on how sperm moves through fluid
- Before now, a complex computer was used to measure the movement of sperm
- But the new mathematical formula is much simpler and easy to use
- The sperm’s whip-like tail creates a characteristic rhythm to push it forwards, while the head is pulled backwards and sideways
During conception, around 55 million sperm are released, racing for the ultimate prize of fusing with the egg.
Until now, the complex rhythmic movement of the sperm on its journey has remained a mystery to scientists.
But a new study has come up with a mathematical formula for the movement, which researchers say could help to treat male infertility in the future.
A new study has come up with a mathematical formula for the movement of sperm, which researchers say could help to treat male infertility in the future (artist’s impression)
Researchers from the Universities of York, Birmingham, Oxford and Kyoto found that the sperm’s tail creates a characteristic rhythm that pushes the sperm forwards, while the head is pulled backwards and sideways.
Successful fertility relies on how sperm moves through fluid, but until now, the details of this movement have been difficult to study.
Dr Hermes Gadêlha, from the University of York’s Department of Mathematics, said: ‘In order to observe, at the microscale, how a sperm achieves forward propulsion through fluid, sophisticated microscopic high precision techniques are currently employed.
‘Measurements of the beat of the sperm’s tail are fed into a computer model, which then helps to understand the fluid flow patterns that result from this movement.
‘Numerical simulations are used to identify the flow around the sperm, but as the structures of the fluid are so complex, the data is particularly challenging to understand and use.
‘Around 55 million spermatozoa are found in a given sample, so it is understandably very difficult to model how they move simultaneously.
‘We wanted to create a mathematical formula that would simplify how we address this problem and make it easier to predict how large numbers of sperm swim.
‘This would help us understand why some sperm succeed and others fail.’
By analysing the movements of the sperm, the researchers were able to come up with a relatively simple mathematical formula.
The researchers found that the sperm’s tail creates a characteristic rhythm that pushes the sperm forwards, while the head is pulled backwards and sideways (artist’s impression)
The formula removes the need for complex and expensive computer simulations that are currently needed to understand sperm’s movement.
The researchers found that the sperm is able to make contradictory movements, such as moving its head backwards, to propel itself towards an egg.
The whip-like tail of the sperm has a particular rhythm that pulls the head backwards, countering some of the friction that is created due to their tiny sizes.
Dr Gadêlha said: ‘It is true when scientists say how miraculous it is that a sperm ever reaches an egg, but the human body has a very sophisticated system of making sure the right cells come together.
‘You would assume that the jerky movements of the sperm would have a very random impact on the fluid flow around it, making it even more difficult for competing sperm cells to navigate through it, but in fact you see well defined patterns forming in the fluid around the sperm.
The researchers now hope to create a model for predictions on larger numbers of sperm. They also believe that it will have implications for new innovation in male infertility treatment (stock image)
‘This suggests that sperm stirs the fluid around in a very coordinated way to achieve locomotion, not too dissimilar to the way in which magnetic fields are formed around magnets.
‘So although the fluid drag makes it very difficult for the sperm to make forward motion, it does coordinate with its rhythmic movements to ensure that only a few selected ones achieve forward propulsion.’
The researchers now hope to create a model for predictions on larger numbers of sperm.
They also believe that it will have implications for new innovation in male infertility treatment.