In spermatozoa of many higher animals, the acrosome is an organelle that develops over the anterior half of the spermatozoon's head. It is a cap-like structure derived from the Golgi apparatus. In Eutherian mammals, acrosome formation is completed during testicular maturation. The acrosome contains digestive enzymes (including hyaluronidase and acrosin) needed to penetrate the zona pellucida covering the ovum.
Acrosome reaction
When the sperm comes in contact with ZP3 in the zona pellucida, this reaction takes place, during which actin polymerizes to form the acrosomal process; also, the acrosomal vesicle fuses with the plasma membrane of the egg cell, and digestive enzymes are released from the sperm to digest the zona pellucida and give access to the egg.
See also
 | This biology article is a stub. You can help Wikipedia by expanding it. |