Hyaluronidase PH-20 is also known as Sperm adhesion molecule 1 (SPAM1) and Sperm surface protein PH-20, which belongs to the glycosyl hydrolase 56 family, SPAM1 / PH-20 is expressed in testis. SPAM-1 / PH20 random hydrolysis of (1->4)-linkages between N – acetyl – beta – D – glucosamine and D-glucuronate residues in hyaluronate. SPAM-1 / PH20 involved in sperm-egg adhesion. Upon fertilization sperm must first penetrate a layer of cumulus cells that surrounds the egg before reaching the zona pellucida. The cumulus cells are embedded in a matrix containing hyaluronic acid which is formed prior to ovulation. SPAM1 aids in penetrating the layer of cumulus cells by digesting hyaluronic acid.