This study was carried out to investigate the effect of biological factors on the in vitro production(IVP) of bovine oocytes for development of simple culture methods and medium. Oocytes from the slaughterhouse ovaries were matured and fertilized using general protocol and this study was examined if there were necessary to co-culture, media change, media type and embryo density. This results were as follows: 1. The development rate according to co-culture with cumulus cells and non co-culture as drop culture was not significantly different in cleavage (68.9 vs 71.7%), 8-cell stage (41.2 vs 44.1%) and blastocyst stage (12.2 vs 13.8%), respectively (p<0.05) 2. The blastocyst development rates in YS and CRIaa were higher than that in TCM199 (12.4, 10.4 vs 3.7%), but the cleavage (69.0, 77.8 and 61.0%) and 8-cell stage (31.7, 37.0 and 35.7%) development accoring to YS, TCM199 and CRIaa ws not significantly different, respectively (p<0.05). 3. There was no significantly different in cleavage (62.6, 59.5 and 61.2%), 8-cell(34.7, 37.9 and 34.0%) and blastocyst (9.5, 11.6 and 12.8%) development among medium change time as control, Group I and Group II, respectively (p<0.05). 4. Blastocyst formation of 8-cell stage according to embryo density was not significantly different in 1, 10 and 25 embryos (27.3, 22.5 and 34.0%), respectively (p<0.05). These results indicated that simple culture system could reduce bovine IVP embryos as drop culture as non co-culture system, high density embryo (25 embryos/50 1 drop). YS defined medium and no medium change for whole culture period, although other biological factors need to examine in order to produce efficient IVP bovine embryos.

This study was conducted to enhance the efficiency of embryo transfer and embryos produced in vitro according to select good quality blastocyst among in vivo or in vitro produced embryos. After middle blastocys(MB) and late blastocyst(LB) stages embryos that developed in vitro for 7∼8 days were treated hypertonic solution(380 mOsm or 600 mOsm) and the rate of development to hatched blastocyst(HB) was examined. The results obtained were summarized as follows: The proportion of embryos developed to HB was higher than that of control regardless of hypertonic solution treatment. However, it was related to culture time in hypertonic solution The propotrion of embryos developed to HB of morphologically recovered embryos in 380 nOsm solution ws higher than that of morphologically shrinked embryos. However, treatment time was not significantly different the rates of HB development. Especially, the proportion of embryos developed to HB of morphologically recovered embryos of the 30-min-treated group was significantly higher than that of control (p<0.05). The results suggest that hypertonic solution treatment should enhance the efficiency for criterion of transferable blastocyst quality.