Explain the penetration the male gamete to the egg cell

Question

Explain the penetration the male gamete to the egg cell? How does the female gamete defend itself from the entry of more gametes after the entry of the first sperm cell?

Answer 1

The sperm cell that arrives at the egg cell activate the acrosome response, a procedure in which hydrolytic enzymes of the acrosome are freed on the exterior surface of the zona pellucid (the protective cover that surrounds the egg cell). A part of this cover is digested by the acrosomal enzymes permitting the sperm cell to attain the plasma membrane of the egg cell carrying out fecundation. At the point that the sperm cell establishes contact with the egg cell membrane a chemical change of this membrane happens. Enzymes secreted by exocytosis (cortical reaction) create the zona pellucida unable to bind to other sperm cells (zonal reaction) and other male gametes can’t enter the egg cell.