Why is normal fertilization of one mature ovum usually performed by only one mature sperm even though hundreds of millions of sperm are present in the seminalfluidofone ejaculation?

Question

Quizplus · Accepted Answer

When the sperm binds with and then penetrates the plasma membrane of the ovum, several different processes occur. First, the ovum's plasma membrane changes its electrical charge, preventing any other sperm from entering. Only the fertilizing sperm's tail and midsection drop off and do not enter the ovum; the other sperm remain motile but cannot penetrate the ovum's plasma membrane. It is not the nuclear membrane that prevents two (dispermy) or more sperm from fertilizing a single ovum. Although the pH of fluid in the female reproductive tract can inhibit acrosomal enzyme activity, this is not what prevents dispermic fertilization.

Why Is Normal Fertilization of One Mature Ovum Usually Performed