Did you know that it is the egg that chooses the sperm, not the other way around?

Sperm meet the egg, fertilization takes place and babies are formed. Simple? Not as much as it seems! Learn more about the concept of female or endometrial receptivity: women’s freedom of choice. Giving a little emphasis to the subject, we find that it is the eggs who really choose.

As Scott Gilbert, a developmental biologist at Swarthmore College (USA) puts it, “The egg evaluates the sperm before eliminating it from the race or classifying it as suitable.” Therefore, fertilization is not a random event, but selection at the cellular level.

After much research, it has been proven that, in addition, eggs tend to attract, in particular, a certain type of sperm, provided the opportunity is favourable.

O incredible.club he was delighted to discover this study, according to which eggs are selective, having their own criteria for choosing sperm.

Virtually every couple planning to increase their family believes that, in the reproduction process, it is the sperm that runs in search of the egg. But let’s start from the beginning. All the sperm are ready, the egg is at its healthiest, and that’s when the race begins! As we were taught in school, millions of sperm are directed towards a single egg. When an X meets an X, a girl is born. And when an X meets a Y, the genetic result is a boy.

However, we are now going to begin the process of unlearning that lesson.

Running? None of that. It was never a race, as the winner goes through a selection process. Almost like the selection process of a candidate for a vacancy. To put it more simply, the egg previously chooses the type of sperm with which it will allow itself to be penetrated.

Studied and explained by scientist Dr. Joseph H. Nadeau of The Pacific Northwest Research Institute (PNRI) in Seattle, USA, ova are neither submissive nor fragile, but play a key role in the reproduction process. And, contrary to popular theory, the sperm does not rush towards the egg. Just the opposite happens.

As the previously mentioned Pacific Northwest Research Institute explains, it is the egg that accepts or discards a sperm depending on its genetic load, making sexual selection at the cellular level something much more complex.

It sounds strange, but the truth is that such an obvious process has been misjudged for a long time.

Mendel’s law is, by definition, like the law of segregation. It is also called the law of genetic inheritance, according to which each gene has its corresponding homologue. The next step is the process of “random fertilization”, in which genes are randomly divided into gametes that carry only one copy. However, recent studies have completely rejected this theory.

Nadeau performed two experiments separately, suggesting an entirely different theory. His intention was to produce specific predictable ratios of gene combinations in the offspring (according to Mendel’s laws). However, he was unsuccessful.

The first test involved the use of female mice with a normal gene and a modified one in order to increase the chances of developing testicular cancer. The male mice had all the normal genes. The result was in accordance with Mendel’s law.

Experiment 2: On occasion, Nadeau reversed reproduction. He gave the male mice the modified cancer gene, while the female mice had all the normal genes. And there it was! What was surprising was the discovery that only 27% had received the mutated version, when experts had expected the result to be 75%.

What we learned in school about normal and modified versions of DND1 in the mother and father is a totally lagged version. The conclusion of all this was to be able to classify fertilization as non-random, proving the existence of a mechanism that allows the egg to choose the sperm with the normal gene, and not with the modified one. In scientific terms, this is called “genetically biased fertilization”.

What does that mean? Has it always been like this and the best scientists in history even noticed the mistake?

Nadeau gave strong reasons to support this newly developed theory. He believed there were two possibilities to support the thesis.

1. The attraction between sperm and eggs is largely linked to the folic acid molecule. The metabolism of vitamin B or folic acid is different in an egg and a sperm. These same changes may represent the decisive factor for the attraction between egg and sperm.

2. Sperm are already present in the female genital tract when they go to the egg. And the egg may not be fully developed or healthy during that time. There is a possibility that the egg influences cell division, which is why its genes may also be suitable for the sperm.

A curious theory, which changes our knowledge on the subject. Don’t forget to leave a comment with your impressions of this recent discovery.