Zona pellucida dissolution enzymes of the rabbit sperm head.

Enzymes which dissolve the zona pellucida have been extracted from the rabbit sperm head and characterized as having the enzymic properties of hyaluronidase and trypsin. Their combined actions produce a rapid and complete dissolution of the zona pellucida, but the vitellus and its membrane are unaffected by prolonged exposure to this enzyme complex. Inhibition of the proteolytic component with lima bean or soybean inhibitors of trypsin prevents dissolution of the zona pellucida by the extract.