In mammals, the acrosome reaction releases hyaluronidase and acrosin. The acrosomal reaction begins when the sperm comes into contact with the oocyte's zona pellucida. Upon coming into contact with the zona pellucida, the acrosomal enzymes begin to dissolve and the actin filament comes into contact with the zona pellucida. Hyaluronidase enzymes present on the surface of the sperm helps sperm to enter into the ova through the layer of granulosa cells.