The structure of the mature sperm contains a tail, middle section having mitochondria and a head part. The tip of the head part contains acrosome and nucleus. The sperm at maturity, contains a cap like structure at the anterior end. It is termed as acrosome. In this structure, enzymes are present which help the sperm to penetrate into the egg for fertilization. The acrosome allows the plasma membranes of both the cells to fuse and fertilization takes place.