Facilitates sperm penetration into the layer of cumulus cells surrounding the egg by digesting hyaluronic acid. Involved in induction of the acrosome reaction in the sperm (PubMed:20586096). Involved in follicular atresia, the breakdown of immature ovarian follicles that are not selected to ovulate. Induces ovarian granulosa cell apoptosis, possibly via apoptotic signaling pathway involving CASP8 and CASP3 activation, and poly(ADP-ribose) polymerase (PARP) cleavage (PubMed:18653706). Has no hyaluronidase activity in embryonic fibroblasts in vitro (PubMed:18234732). Has no hyaluronidase activity in granulosa cells in vitro (PubMed:18653706). Random hydrolysis of (1->4)-linkages between N-acetyl-beta-D-glucosamine and D-glucuronate residues in hyaluronate. Optimum pH is 7. Higher activity at pH 4 than at pH 7 in sperm. Mostly present in low-density vesicles. Low levels in higher density vesicles of late endosomes and lysosomes. Localized in punctate cytoplasmic vesicles and in perinuclear structures, but does not colocalize with LAMP1 (PubMed:18234732). Localized on the plasma membrane over the acrosome and on the surface of the midpiece of the sperm tail (PubMed:20586096). Expressed in testis, epididymal tissue, epididymal luminal fluid (ELF), acrosome-intact (AI) sperm and caput (CAP), corpus (COR) and caudal (CAU) sperm. Higher expression in sperm than testis (at protein level) (PubMed:20586096). Liver, kidney, skin, brain, stomach and testis (PubMed:11929860). Expressed mainly in granulosa cells of the ovaries. Expressed in small and large antral follicles. Not present in theca or stroma cells (PubMed:18653706). Expressed in testis and liver (PubMed:18762256). Expressed in testis and CAP, COR, and CAU epididymis tissue (PubMed:20586096). Up-regulated expression in apoptotic granulosa cells and in atretic follicles of the ovaries (PubMed:18653706). N-glycosylated. No visible phenotype. Both male and female mice are viable. Skeletal features, joints, whole-body weights, organ weights, organ morphologies and the serum hyaluronic acid (HA) levels are normal. No evidence of glycosaminoglycan accumulation, including vacuolization, in tissues analyzed including liver, lung, kidney, spleen, skin, fat, testes and seminal vesicles at 12-14 months of age. No difference in tissue organization or connective tissue thickness. Only a subtle change in the alveolar structure and extracellular matrix thickness in lung tissue sections at 12-14 months of age. Lungs have larger alveoli and more areas of thickened interstitium. Lung tissues from 6 months old mice show more immature alveoli compared to wild-type (PubMed:18762256). Mice are fully fertile (PubMed:18762256, PubMed:20586096). Sperm show delayed cumulus penetration and reduced acrosomal exocytosis (PubMed:20586096). Belongs to the glycosyl hydrolase 56 family.