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How do the acrosome and its enzymes help a sperm cell enter an egg?

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Front view anatomical diagrams of the male and female reproductive systems, with labeled organs including penis, testis, prostate gland, uterus, ovary, and vagina. — human reproductive system Organs and structures of the male and female reproductive systems.

The acrosome is a specialized structure located at the anterior tip of a spermatozoon that facilitates the penetration of the egg by releasing specific enzymes.12

When a sperm contacts the egg, it undergoes the acrosome reaction, where the acrosomal vesicle bursts and releases its contents. This process aids entry in the following ways:1

Enzymatic Digestion: The acrosome releases enzymes such as hyaluronidase, which breaks down the hyaluronic acid binding the cells of the outer egg envelope (the corona radiata) together, allowing the sperm to pass through.1
Dissolution of Barriers: In many species, the acrosome releases a substance called lysin, which dissolves the egg's protective vitelline coat.1
Membrane Fusion: Following these structural changes, the acrosomal membrane forms a tubule that extends to the egg surface, establishing continuity between the two cells and allowing the sperm nucleus to enter the egg's interior.1

These mechanisms ensure the sperm can successfully traverse the complex egg coats to achieve fertilization.13