The acrosome is an organelle that develops over the anterior half of the head in the sperm cells or spermatozoa of many animals. It is a cap-like structure and is derived from the Golgi.
It contains digestive enzyme including hyaluronidase and acrosin which break down the outer membrane of the ovum (zona pellucida), allowing the haploid nucleus in the sperm to join with the haploid nucleus in the ovum.