In spermatozoa (also known as sperm/sperm cell) of many animals, the Acrosome is an organelle that develops over the anterior half of the sperm's head. It is a cap-like structure derived from the Golgi apparatus. Acrosome formation is completed during testicular maturation. In Eutherianmammals the acrosome contains digestive enzymes (including hyaluronidase and acrosin). [1] These enzymes breakdown the outer membrane of the ovum called the zona pellucida, allowing the haploidnuclei in the sperm to join with the haploid nucleus found in the ova.