The studies were carried out to investigate the effects of co-culture with cumulus cells and oviduct epithelial cells on the in vitro fertilization and cleavage rate of bovine follicular cocytes and to determine the optimum thawing temperature and equilibration time on in vitro developmental rate of frozen bovine embryos. The ovaries were obtained from slaughtered Korean native cows. The follicular oocytes were cultured in TGM-199 medium containing 10 IU /ml의 PM SG, 10 IU /ml의 hCG, ip g/ml의 -estradiol and 10% FCS for 24~48 hrs in incubator with 5% in air at 38.5. The bovine embryos following dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquld nitrogen and thawed in 3 water. Survival rate was defined as developmental rate on in vitro culture or FDA-test. The results are sunanarized as followes :1. The in vitro fertilization and in vitro developmental rates of bovine oocytes co-cultured with cumulus cells in TCM499 medium were 75.0~76.8% and 17.3~27.6%, respect-ively. And in-vitro fertilization rates of cumulus-enclosed oocytes(55.4%)were significantly(p<0.05) higher than cumulus-denuded oocytes (23.1%). 2. The in vitro fertilization and in vitro developmental rates of bovine oocytes co-cultured with l l04cells /ml, 1 x l06cells /ml, lx l08cells /ml and 1 x l015cells /ml oviduct epithelial cells in TCM-199 medium were 74.5~77.8% and 15.7~21.20 respectively.3. The in-vitro fertilization and in vitro developmental rates of bovine oocytes cocultured in '1CM-199 media containing PMSG, hCG, PMSG+hCG. PMSG+-estradiol, hCG+-estradiol 0 to 40 hrs after insemination were 74.0~77.4% and l8.9~23.l%, re-spectiv ely.4.The survival rates of bovine embryos thawed after rapid freezing in the freezing medium containing a various concentration of sucrose added 1.5M and 2.OM glycerol,DMSO and propanediol were 23.5~31.4% and 20.6~34.l%, respectively. 5. The temperature thawed at 3 after rapid freezing of bovine embryos resulted in a significantly higher embryos survival rate than did at 2 and 35.6. The equilibration time on the survival rates of bovine embryos was attained after short period of time(2.5~5 min.) in the freezing medium higher than long period of time (10~20min.). (Key words : bovine embryos, co-culture, freezing, in vitro development)

The studies were carried out to investigate the effects of bisection method and with and without-zona pellucida of embryos on in vitro developmental rate bisected embryos by micromanipulator, micropipette and pipetting. The ovaries were obtained from slaughtered Korean native cows. The follicular oocytes were cultured in TCM-199 mediurn containing 10 IU /ml의 PMSG(Sigma, USA), 10 IU /ml의 hCG, 1g /ml의 -estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% in air at 38.5 and then, matured oocytes were again cultured for 12~ 18 hrs with motile capacitated sperm by preincubation of heparin. Bisected embryos cultured for 1~5 days in 20% FCS + TCM-199 medium. Survival rate was defined as developmental rate on in vitro culture or FDA-test. The results are summarized as follows :1. The survival rates of bisected bovine embryos by micromanipulator and micropipett were 29.2% and 19.1%, respectively. The rates of non-bisection embryos(46.7%) were significantly higher than those of bisection embryos. 2. The in vitro developmental rates of bisected bovine embryos by micromanipulator, micropipett and pipetting method were 32.4%, 19.4% and 25.6%, respectively.3. The in vitro developmental rates of with and without-zona pellucida of bisected bovine embryos by raicromanipulator were 30.8% and 25.0%, respectively. The rates of nonbisection embryos(53.1%) were significantly higher than those of bisection embryos.

This study was carried out to investigate On in vitro fertilization, survival rate and developmental rate of rapidly frozen bovine immature oocytes. Immature oocytes cultured for 1, 12, 24, 48 hours in 20% FCS + TCM-199 medium and thereafter rapidly freezing-thawed oocytes inseminated with capacitated sperm. The immature oocytes following dehydration by 1.5M DMSO + 2.0M glycerol + 0.25M sucrose + TCM 199 media + 20% FGS were directly plunged into liquid nitrogen and thawes in 3 water. Rapid freezing embryos co-cultured in 20% FCS + TCM-199 media containing hormones(21U/mL PMSG, 21U /mL hGG and 1 g /mL 17-estradiol) and cumulus cells(1 x 105-6 cells). Survival rate was defined as development rate on in vitro culture or FDA-test. The results are summarized as follows ; 1. The in vitro maturation and fertilization rate of immature bovine oocytes on in vitro maturation period(1, 12, 24, 48 hrs) before rapid freezing4hawed were 57.1%, 45.7%, 37.1%, 25.7% and 40.0%, 31.4%, 20.0%, 11.4%, respectively. 2. The survival rate of immature bovine oocytes on in vitro maturation period(1, 12, 24, 48 hrs) before rapid freezing-thawed were 33.3%, 26.7%, 20.0%, and 10.0%, respectively. The survival rate of rapid freezing4hawed immature oocytes was significantly lower than that of non-freezing oocytes. 3. The survival rate of rapid freezing4hawed excellent and good bovine embryos co-cultured in 20% FCS + TCM-199 media containing hormones(PMSG, hCG, 17-estradiol) and cumulus cells 4 to 5 hrs and 20 to 24 hrs were 35.0%, 15.0% and 25.0%, 15.0% and 40.0%, 20.0% and 30.0%, 15.0%, respectively. The survival rate of embryos co-cultured in TCM-199 media containing hormones and cumulus cells was significantly higher than that of non co-culture.

The study was conducted to determine the optimal hormone and glucose levels during the in vitro culture of bovine oocytes matured and fertilized in vitro for blastocyst development. Oocytes matured in TCM 199 + 10% FCS + hormones and glucose were fertilized in vitro in a TALP medium with swim up separated and heparin-treated epididymal cauda spermatozoa. Oocytes were cultured for 2~5 days in synthetic oviduct fluid medium (SOFM) supplemented with 10% FGS and with different hormone and glucose levels, and further cultured 5 days same medium in SOFM. The results are summarized as follows : The in vitro maturation and penetration rates of porcine oocytes cultured in TCM 199 media containing PMSG, hCG, PMSG + hCG, hCG + estradiol, PMSG + estradiol 0 to20 hours after insemination were 88.0% and 81.8%, 82.6% and 68.4%, 80.0% and 75.0%, 80.0% and 65.0%, 77.3% and 64.7%, respectively. The in vitro maturation and penetration rates of porcine oocytes cultured in TCM 199 media containing PMSG, hCG, PMSG + hCG, hCG + estradiol, PMSG + estradiol 20 to 40 hours after insemination were 92.0% and 87.0%, 92.0% and 82.6%, 91.3% and 81.0%, 85.2% and 73.9%, 87.5% and 81.0%, respectively. The cleavage and in vitro developmental rates to blastocyst of porcine oocytes cultured in TCM 199 media containing 0.05 mM, 0.10 mM, 0.30 mM, 0.50 mM, 1.00 mM, and 3.00 mM glucose lelvels 0~3 days after insemination were 31.5~48.1% and 10.0~16.7%, respectively. The cleavage and in vitro developmental rates to blastocyst of porcine oocytes cultured in TCM 199 media containing 0.05 mM, 0.10 mM, 0.30 mM, 0.50 mM, 1.00 mM, and 3.00 mM glucose levels 4~8 days after insemination were 30.0~53.8% and 8.7~19.2%, respectively. The cleavage and in vitro developmental rates to blastocyst were higher in TCM 199 media containing various glucose levels 0~3 days after insemination than 4~8 days.