Mystery of how sperm swim revealed in mathematical formula

March 20, 2017, University of York
Mystery of how sperm swim revealed in mathematical formula
The research demonstrated that the sperm has to make multiple contradictory movements. Credit: University of York

Researchers have developed a mathematical formula based on the rhythmic movement of a sperm's head and tail, which significantly reduces the complexities of understanding and predicting how sperm make the difficult journey towards fertilising an egg.

Researchers at the Universities of York, Birmingham, Oxford and Kyoto University, Japan, found that the 's tail creates a characteristic rhythm that pushes the sperm forward, but also pulls the head backwards and sideways in a coordinated fashion.

Successful fertility relies on how a sperm moves through fluid, but capturing details of this movement is a complicated issue.

The team aim to use these new findings to understand how larger groups of sperm behave and interact, a task that would be impossible using modern observational techniques. The work could provide new insights into treating male infertility.

Simplify the problem

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."

Coordinated rhythm

By analysing the head and tail movements of the sperm, researchers have now shown that the sperm moves the fluid in a coordinated rhythmic way, which can be captured to form a relatively simple mathematical formula. This means complex and expensive computer simulations are no longer needed to understand how the fluid moves as the sperm swim.

The research demonstrated that the sperm has to make multiple contradictory movements, such as moving backwards, in order to propel it forward towards the egg.

The whip-like tail of the sperm has a particular rhythm that pulls the head backwards and sideways to create a jerky fluid flow, countering some of the intense friction that is created due to their diminutive sizes.

Miraculous

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 around it, making it even more difficult for competing to navigate through it, but in fact you see well defined patterns forming in the fluid around the sperm.

"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."

Now that the team has a that can predict the movement of one sperm, the next step is to use the model for predictions on larger numbers of cells. They also believe that it will have implications for new innovations in infertility treatment.

The research is published in the journal Physical Review Letters.

Explore further: Researchers describe how sperm can lose their way

More information: Coarse-graining the fluid flow around a human sperm. journals.aps.org/prl/accepted/ … 0c41b355d03e216a84f6

Related Stories

Researchers describe how sperm can lose their way

February 24, 2017

Sperm tails are actually complex propellant and navigational devices that help push them through fluids and navigate around complex terrain of the female oviduct. Now researchers at Yale and Harvard Universities have identified ...

Sperm found to swim in groups when in viscoelastic fluids

March 18, 2016

(Phys.org)—A team of researchers led by Chih-Kuan Tung of North Carolina A&T State University has found evidence that bull sperm tend to move closer together forming groups when swimming in viscoelastic fluids. Tung gave ...

Big sperm don't always win the race

January 31, 2014

When females mate with more than one male, each one's sperm has to compete to get to her eggs. Until now, researchers had thought the fastest sperm would dominate.

Recommended for you

Walking crystals may lead to new field of crystal robotics

February 23, 2018

Researchers have demonstrated that tiny micrometer-sized crystals—just barely visible to the human eye—can "walk" inchworm-style across the slide of a microscope. Other crystals are capable of different modes of locomotion ...

Researchers turn light upside down

February 23, 2018

Researchers from CIC nanoGUNE (San Sebastian, Spain) and collaborators have reported in Science the development of a so-called hyperbolic metasurface on which light propagates with completely reshaped wafefronts. This scientific ...

Recurrences in an isolated quantum many-body system

February 23, 2018

It is one of the most astonishing results of physics—when a complex system is left alone, it will return to its initial state with almost perfect precision. Gas particles, for example, chaotically swirling around in a container, ...

Seeing nanoscale details in mammalian cells

February 23, 2018

In 2014, W. E. Moerner, the Harry S. Mosher Professor of Chemistry at Stanford University, won the Nobel Prize in chemistry for co-developing a way of imaging shapes inside cells at very high resolution, called super-resolution ...

Hauling antiprotons around in a van

February 22, 2018

A team of researchers working on the antiProton Unstable Matter Annihilation (PUMA) project near CERN's particle laboratory, according to a report in Nature, plans to capture a billion antiprotons, put them in a shipping ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.