Do sperm race (really)?

Before setting off to invade the egg, sperm first pass through the male's tubules, the vas deferens and then the prostate, to mix with sperm, before being expelled through the urinary meatus. Once they come out into the open, they realize it Sprints, individual regattas or group mountaineering ?

The answer is with Dr. Gilbert Bou Jaoude, graduate of Andrology at the University of Lille and Regular contributor on charles.co It is an amazing journey for sperm, which lasts from six to eight hours.

Do sperm move in semen?

When sperm bathe in sperm, the intuitive (but wrong) idea would be that they swim, carried by sperm, before reaching the egg. Dr. Gilbert Bou Jaoude specifies: “ Sperm depends on the sperm to be in the female environment and then depends on its movement in a hostile environment. Sperm is the plane that takes them to their safe destination. And then they run. »

Once it enters the female body, sperm plays a role Independent cells. If there are many other cells in the human body that function independently (think of intestinal cells or muscle fibers), then the sperm is the only cell in the human body that The goal is to move outwards. In this regard, its movement, such as the shape of its head or its endurance, are essential criteria for its potential success.

Individual enemy or teamwork?

By Dr. Gilbert Bou Jaoude: “ We know that the entire team will not come out on top, but everyone will work until only one team wins. The mathematical model that comes to mind is Group bike races. There are millions who will break up, fall, and some who will reach the end, rather tired. »

In particular, Speed ​​of whiplash Allowing a better speed of access to the egg is not an indicator of efficiency. Doctoral student's latest work Benjamin Rafo (2016) within limitsPierre and Marie Curie University prove that: Contrary to what we thought, whiplash is used not only to reach the egg, but also to stimulate fertilization. » The overzealous whip (3 oscillations per second) will certainly reach quickly near the egg, but will not allow it to enter. The sperm revolve around the egg without being able to penetrate it. It will take two oscillations per second, no more, no less.

The arrival of the first sperm will also prepare the egg membrane. So it is neither the fastest nor the slowest that wins. It is teamwork where speed is one of the criteria for success among others.

Does the egg have a say?

the Recent work published in the Royal Society (2020) will prove that eggs have preferences with respect to certain sperm. by So-called “chemoattractant” molecules. Contained in the follicular fluid (fluid found in each egg), additional selection will be made on the side of the female gametes.

Moreover, if the goalkeeper chooses the color of the ball that goes into the goal, we understand that a sprint is not the most obvious sports metaphor for the journey of sperm.

Which sport do you choose then? Less than ten years separate us from the last two studies, and the evidence for this is in terms of:Playful interaction (Sperm vs. Egg Discussion) We still have a lot to learn.

Dr. Gilbert Bou Jaoude reminds us: “ There are still many gray areas, even if science is advancing! 50 years ago, the number of infertility cases in which people succumbed due to an “unknown cause” was twice as high. But there are still many cases where we can't find the reason, and I don't believe in mysterious reasons, like “it's in the head.” It gives us more knowledge. »

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