During fertilization, the ovum guides the sperm to it, but not all of them react to the chemical signals that reach them. In the end, the ovum "chooses" the sperm most receptive to the chemoattractant molecules it secretes.
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In nature, the courtship displays of some cash are inventive treasures that allow females to choose the male whose heritage genetic will give the best offspring. How females choose is a closely guarded secret.
But for mammals, this “feminine selection” also takes place at a cellular level. Indeed, the ova, through molecules chemoattractantes, select the best sperm. This phenomenon has been described in mice or cetaceans but remains relatively unknown in humans although we already know that the molecules secreted byovum guide them sperm up to him.
A study published in Proceeding of the Royal Society B suggests that human ova also choose from sperm that present themselves to them by the same mechanism. And sometimes, those that respond best to chemical molecules do not necessarily belong to the woman's love partner.
The egg attracts sperm
This experiment was carried out on couples who are followed for fertilization in vitro. Scientists have recovered the fluid that surrounds the ovum in follicles and in which it pours its chemoattractant molecules, as well as the sperm of the participants. Then they observed the behavior of sperm from several donors in the face of different liquids follicular.
The results obtained suggest that sperm respond differently to each follicular fluid. The eggs, thanks to the molecules they secrete around them therefore attract sperm belonging to a specific man.
" A woman's follicular fluid was better at attracting sperm of a given man, when another woman's follicular fluid was better at attracting another man's sperm "Explains Professor Fitzpatrick of the University of Stockholm and first author of the study. But the sperm of the man preferred by the ovum does not necessarily belong to his loving companion.
Chemistry rather than love
Indeed, scientists tested the response of sperm to follicular fluid from a couple or two strangers. Conclusion, the sperm of a given man do not accumulate more around the follicular fluid of his partner. Love therefore does not translate into a better affinity of sperm for the ovum.
And for good reason, sperm have only one goal: to swim to the egg to fertilize it. He therefore has no interest in being difficult, according to Professor Fitzpatrick. On the other hand, the ovum has every reason to choose carefully the sperm which will fertilize it for its genetic characteristics or for its affinity for the chemoattractants which it secretes.
So the cause of the problems fertility could not be, among other things, too slow or few sperm or a defect ofovulation, but a lack of compatibility biochemical between the ovum and the sperm.
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