Sperm crawl and collide on way to egg, researchers say

May 7, 2012

Scientists at the Universities of Birmingham and Warwick have shed new light on how sperm navigate the female reproductive tract, 'crawling' along the channel walls and swimming around corners; with frequent collisions.

Research results published today in the (PNAS) provide fresh insight into how might find their way to the egg that will help to inform future innovation in the struggle to treat .

Scientists led by Dr Petr Denissenko, of the School of Engineering at the University of Warwick, and Dr Jackson Kirkman-Brown, lead in at the University of Birmingham, explored what properties distinguish the tens of cells which make it to the egg from the millions of ejaculated.

Contrary to popular belief, the authors report, sperm rarely swim in the central part of the three-dimensional female tract, instead travelling along the walls, meaning in the body they are negotiating complex and convoluted channels filled with viscous fluids.

To study cell behaviour in confined space, cells were injected into hair-thin microchannels.

"When the channel turns sharply, cells leave the corner, continuing ahead until hitting the opposite wall of the channel, with a distribution of departure angles, the latter being modulated by fluid viscosity," the reports' authors said.

"Specific wall shapes are able to preferentially direct motile cells," the authors report.

"As a consequence of swimming along the corners, the domain occupied by cells becomes essentially one-dimensional.

"This leads to frequent collisions and needs to be accounted for when modelling the behaviour of populations of migratory cells."

Dr Kirkman-Brown, who is also Science Lead for the Birmingham Women's Fertility Centre, comments: "Two key questions in reproduction are:

  • how are the millions of sperm selected down to around ten that reach the oocyte?: and
  • Can we use a similar method to select sperm for fertility treatments?
"In basic terms – how do we find the 'Usain Bolt' among the millions of sperm in an ejaculate. Through research like this we are learning how the good sperm navigate by sending them through mini-mazes. "

Dr Denissenko of the University of Warwick added: "Sperm cell following walls is one of those cases when a complicated physiological system obeys very simple mechanical rules.

"I study fluids in a variety of environments, but moving to work with live human sperm was quite a change.

"I couldn't resist a laugh the first time I saw sperm persistently swerving on tight turns and crashing head-on into the opposite wall of a micro-channel.

"More seriously, it's great being part of an internationally leading team based out of the Midlands addressing a key problem."

Dr Kirkman-Brown concludes: "Previous research from the group indicates that the shape of the sperm head can subtly affect how the sperm swim.

"Combined with this data we believe new methods of selecting sperm, perhaps for quality or even in certain non-human species for sex may become possible."

The researchers suggest that the combined effect of the fluid rheology and three-dimensional architecture should be taken into account in future in-vitro studies.

Explore further: Rodent sperm work together for better results

More information: Human sperm swimming in micro-channels, Proceedings of the National Academy of Sciences (2012).

Related Stories

Rodent sperm work together for better results

January 24, 2007

Although, sperm are inseminated in millions each sperm goes it alone. However, under some circumstances it might be advantageous for sperm to cooperate with one another. This is especially likely to be the case when females ...

Viagra could be harmful to fertility

February 25, 2008

A study to be published in the British medical journal Fertility and Sterility suggests that Viagra could harm men's fertility.

Men with deep voice may be lacking in sperm: study

January 9, 2012

(Medical Xpress) -- Women look for tall, dark and handsome. Those chiseled features and that deep sexy voice have gained the attention of women for generations. However, a new study published in PLoS ONE shows that those ...

Sperm can count

March 7, 2012

The speed at which the calcium concentration in the cell changes controls the swimming behavior of sperm. They can calculate the calcium dynamics and react accordingly.

Recommended for you

Basic research fuels advanced discovery

August 26, 2016

Clinical trials and translational medicine have certainly given people hope and rapid pathways to cures for some of mankind's most troublesome diseases, but now is not the time to overlook the power of basic research, says ...

New avenue for understanding cause of common diseases

August 25, 2016

A ground-breaking Auckland study could lead to discoveries about many common diseases such as diabetes, cancer and dementia. The new finding could also illuminate the broader role of the enigmatic mitochondria in human development.

New method creates endless supply of kidney precursor cells

August 25, 2016

Salk Institute scientists have discovered the holy grail of endless youthfulness—at least when it comes to one type of human kidney precursor cell. Previous attempts to maintain cultures of the so-called nephron progenitor ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Hev
not rated yet May 08, 2012
typical male behaviour -

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.