Abstract
Culture conditions of in vitro fertilized bovine eggs denuded or surrounded with cumulus cells were examined in order to effectively use the simply defined medium, HECM. In experiment 1, the rate of development to the blastocyst stage of denuded eggs was lower than that of eggs co-cultured with cumulus cells. The rate of development to the blastocyst stage of denuded eggs in the HECM medium was higher than that in the medium TCM199. In experiment 2, the effects of oxygen concentrations on the development of denuded and co-cultured eggs were examined in the HECM medium. The rate of development to the blastocyst stage in denuded ova was significantly higher in the 7% O2 condition (21%) than in the 20% O2 condition (0%). In experiment 3, the effect of calf serum (CS) and insulin like growth factor 1 (IGF-1) on the development of denuded eggs cultured in HECM with 7% O2 was examined. The rate of development of CS and IGF-1 improved significantly (13-27%) compared with the control (PVA) (8%). This suggested that the bovine embryo could be effectively cultured in the simply defined medium in vitro when the culture conditions were sufficiently examined, including the elimination of inhibing factors from the culture medium and gas (O2, CO2) pressure.
