What happens during fertilization in humans after many sperms reach close to the ovum?

Explanation

Secretions of acrosome help one sperm enter the cytoplasm of the ovum through the zona pellucida. During fertilization, when multiple sperms reach close to the ovum, they are initially surrounded by a layer of cells called the corona radiata. The acrosome is a structure present at the tip of the sperm head that contains enzymes. These enzymes are released upon contact with the zona pellucida, a glycoprotein-rich layer surrounding the ovum. The acrosomal enzymes help in breaking down the zona pellucida, allowing one sperm to penetrate and enter the cytoplasm of the ovum. This process is known as sperm penetration or sperm-egg fusion. Once a single sperm successfully enters the ovum, the zona pellucida undergoes changes to create a barrier that prevents other sperms from entering.