What Activity During Oocyte Activation Prevents Penetration By Additional Sperm?

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What activity during oocyte activation prevents penetration by additional sperm?
There are to methods consisting of an electrical block and mechanical block, which prevents penetration of additional sperms during oocyte activation. Electrical block involves the absences of fertilization (the oocyte contains a negative charge within and the sperm a positive charge). For instance, if an oocyte comes into contact with a sperm the negative charge within the oocyte changes to positive resulting any other sperms from penetrating the oocyte since the repulsive forces between like charges. However, a mechanical block operates primarily in mammals and other animals such as endoplasmic reticulum. The calcium ion stimulates the vesicles to undertake exocytosis of molecules from cortical granules modifying the extracellular membranes such as the vitelline membrane and the zona pellucida to harden preventing polyspermy, therefore, resulting in creating a barrier against ruther sperm penetration. However, in mammals the first sperm to enter into the egg; the cortical granules found in the cortex of the egg secretes a serine protease allowing it to shift its properties of the membrane of the zona pellucida typically the layer found outside the plasma membrane. The protease grinds up the proteins and function as a receptor in binding a sperm (i.e. ZP3 glycoproteins and ZP2) as well as the ones that adhere the cell membrane to the vitelline envelope. The secreted molecules consist of

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