Once the plasma membranes of the egg and sperm fuse, the egg completes meiosis II and undergoes a series of changes that further prevent _____, or fertilization by more than one sperm.

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The process that prevents fertilization by more than one sperm is called polyspermy. Once the sperm fuses with the egg, the egg completes meiosis II and forms the female pronucleus. At the same time, the sperm nucleus forms the male pronucleus. These two pronuclei fuse to form a zygote. The egg also undergoes changes in its membrane potential and the release of cortical granules to prevent additional sperm from fertilizing the egg. This process is called the cortical reaction, which further prevents polyspermy.

Once the Plasma Membranes of the Egg and Sperm Fuse