Penetration of human sperm is a chemical mechanism. In this, acrosome of sperm undergoes acrosomal reaction and releases certain sperm lysins, which dissolve the egg envelope locally and make the path for the penetration of sperm. Sperm lysins are acidic proteins. These sperm lysins contain a lytic enzyme hyaluronidase that dissolves the hyaluronic acid polymers in the intercellular spaces, which holds the granulosa cells of corona radiata together corona penetrating enzyme and acrosin.