EFFECT OF HYALURONIC-ACID ON DEVELOPMENT OF IN-VITRO PRODUCED BOVINE EMBRYOS

The present study was carried out to evaluate the effect of hyaluronic acid (HA) added to the culture medium on bovine embryo development to the blastocyst stage as well as embryo quality and viability after fr eezing and thawing. In vitro matured and fertilized (IVM/IVF) bovine o ocytes from slaughterhouse ovaries were cultured for 8 d in SOFm suppl emented with 4 mg/mL fatty acid-free BSA, either in the absence or pre sence of 1 or 0.5 mg/mL HA. There was a significant increase in blasto cyst yield in the presence of 1 mg/mL (P < 0.01), whereas 0.5 mg/mL HA was ineffective. Cleavage rate and mean number of days to blastocyst formation were unaffected by HA at any concentration. At 1 mg/mL, HA d id not affect either post-freeze survival of Grade 1 and 2 blastocysts or the number of nuclei per blastocyst. Supplementation with HA at 1 mg/mL also significantly enhanced embryo development up to the blastoc yst stage (P < 0.05) in a chemically-defined culture medium without a protein source. It is concluded that supplementation of both semidefin ed and defined culture media with 1 mg/mL HA improves the development of IVM/IVF bovine embryos to the blastocyst stage, without affecting e mbryo quality and post-freeze survival. These results open the possibi lity of including HA in culture media in order to increase the efficie ncy of in vitro blastocyst production from in vitro-matured bovine ooc ytes. (C) 1998 by Elsevier Science Inc.