Egg and sperm: a sticky love story

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For as long as scientists have contemplated reproduction and known about the puzzle pieces we call sperm and egg, they have wondered how they came together. Now researchers at the Swedish medical university Karolinska Institutet have described the structure of the egg receptor that binds with the sperm to cause fertilization. The journal Cell will publish the findings which may in fact in lead to non hormonal methods of birth control.

At the beginning of conception the gametes, egg and sperm, meet up, combine, and create a whole new person. The mystery of that initial attraction is now a little less mysterious with the development of a 3D model of the egg receptor. When the sperm binds to the proteins in the extracellular coat of the egg, the zona pellucida (ZP). Until now the molecular details have been indiscernible.

The research team at Karolinska Institutet led by Luca Jovine discovered and created the image of ZP3 the receptor molecule that binds sperm. Now that the molecular model is available, they can begin exploring how the egg interacts with the sperm at the very first moments of their introduction.

The study indicates which receptor is the one which binds with the sperm and provides new information on the corresponding sperm receptor and also how these two interact with each other. From all of this comes an important implication regarding reproductive control in that new forms of contraception can be developed which target specifically this receptor and need not contain hormones. Additionally, understanding how this “glue” works will give information to scientists about how it doesn’t work and therefore more information regarding some kinds of infertility and how to overcome it.

“The results give a remarkable picture of the female side of fertilization,” says Jovine. “But this is, of course, half the story. The next step will be to tackle the corresponding molecules on sperm that allow it to bind to the egg.”

Source: Karolinska Institutet, ScienceDaily


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