effect of hyaluronic acid in fertilization in vitro of cumulus-free bovine oocytes

bovine oocytes matured in culture were denuded from cumulus cells with hyaluronidase and by repeat pipetting trough a fine pasture pipete and were inseminated with frozen-thawed spermatozoa in a protein-free bo medium containing 5m m-caffeine, l0 mg heparin/ml and with or without polyvinyl pyrrolidone (pvp) and different concentrations of hyaluronic acid. when oocytes were inseminated in the absence of polyvinyl pyrrolidone, no penetration was observed in the absence of hyaluronic acid. however, 9 to 15% penetration was observed in the presence of 0.001 to 1 mg hyaluronic acid. different concentrations of hyaluronic acid did not significantly changed the penetration rates of oocyes. when polyvinyl pyrrolidone was added to the fertilization medium, higher penetration rates (50-64%) were obsetved in different concentrations of hyaluronic acid. in the presence of polyvinyl pyrrolidone, significant higher penetration rates (p