A mass of sperms fight their way through the female reproductive tract to fertilise a egg, says a new research which explored the properties that distinguish the tens of cells which make it to the egg from the millions of sperm cells ejaculated.
Scientists led by Petr Denissenko, from School of Engineering at Warwick University and Jackson Kirkman-Brown, reproductive biologist at the University of Birmingham, explored what properties distinguish the tens of cells which make it to the egg from the millions of sperm cells 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, the journal Proceedings of the National Academy of Sciences reports.
“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, according to a Warwick and Birmingham statement.
“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.”
Kirkman-Brown comments: “Two key questions in reproduction are: How are the millions of sperm selected down to around 10 that reach the oocyte, an egg cell. 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,” said Kirkman-Brown.
Denissenko from 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 cells persistently swerving on tight turns and crashing head-on into the opposite wall of a micro-channel. (IANS)