• Journal of Embryo Transfer
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• v.7 no.2
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• pp.125-131
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• 1992

The nudear changes of bovine oocytes during 24 hrs. of culture for mejotic maturation were examined. Bovine oocytes were collected from small(<2 mm), medium(2~6 mm) and large(>6mm) follicles and classified into three grades by their morphological characteristics. A total of 242 oocytes collected were obtained:from 184 small, 157 medium and 1 large follicles, respectively and were classified into 95 grade I, 155 grade H and 92 grade III oocytes. All the bovine oocytes collected and graded were washed with a basal medium and incubated in groups of 10 for 24 hrs in 5% $CO_2$ and 39$^{\circ}C$. The basal medium used was composed of TCM-199 supplemented with sodium bicarbonate, sodium pyruvate, streptomycin, penicillin G and 10% FCS. The oocytes were cultured in drops of 50,$\mu$l basal medium supplemented with 35$\mu$g /ml FSH, 10$\mu$g /ml LH and 1$\mu$g /ml estradiol-17$\beta$. The oocytes were fixed and examined on their chromosomal status by 1% acetorcein staining in the interval of 3 hrs. Most of the grade I oocytes developed to germinal vesicule stage at 0 to 3 hrs., germinal vesicle breakdown at 6 hrs., metaphase I at 9 to 15 hrs., anaphase I and telophase I at 18 hrs., and metaphase II and the first polar body at 24 hrs. after culture for meiotic maturation. However, it was found that compared to grade I oocytes, grade H and W oocytes reached earlier to germinal vesicle breakdown and most of them developed earlier to M II stage at 21 hrs. after culture.

• Journal of Embryo Transfer
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• v.33 no.3
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• pp.99-105
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• 2018

To determine the differences in the in-vitro ovum maturation process of bovine, we compared the expression of MMPs in these oocytes and cumulus cell throughout oocytes maturated. In an attempt to investigate the effect of MMP activation and inhibitors in total protein of cumulus cell and, oocytes during oocytes maturation, we examined and monitored the localization and expression of MMPs (MMP-2 and MMP-9), TIMPs (TIMP-2 and TIMP-3), as well as their expression profiles (Real-time PCR, Gelatin Zymography and ELISA). Our results that the bovine oocytes MMP-2 and MMP-9 level was significantly associated with the rate of maturity of oocytes (P<0.05). In cumulus cell, MMP-2 was highly expressed in all stages of the oocyte's maturation. The final oocytes maturation exhibited strong gelatinase activity. There was no significant correlation between cumulus cell MMP-9 and the maturation rate of oocytes. However, for the oocyte cytoplasm MMP-9 expression was significant correlation to the maturation oocytes. There was no significant correlation between cumulonimbus cells MMP-9 and oocyte maturation rates; however, for oocyte cytoplasm, MMP-9 expression was significantly correlated with mature oocyte. However, the TIMP-1 and TIMP-2 protein expression patterns are not correlated with the maturation rate of the oocyte. Our results suggest that MMP different expression pattern may regulate the morphological remodeling of oocyte's in the cumulus cell. Further, the MMP-2 expression has a strong relation with a higher maturation rate of the oocyte.

• Korean Journal of Animal Reproduction
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• v.16 no.1
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• pp.7-14
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• 1992

These experiments were designed to investigate the effects of glycosaminoglycans(GAGs), which maybe produced by cumulus cells, on in vitro maturation process of bovine follicular oocytes. The rates of in vitro maturation of bovine oocytes were examined after incubating with the various concentrations of a hyaluronic acid, chondroitin sulfate, or heparin for 26 hours. The results obatained in these experiments were summarized as follows : 1. When the cumulus or removed oocytes treated with hyaluronic acid(200, 400, 800 and 1, 600$\mu\textrm{g}$/ml), the maturation rates of cumulus-removed oocytes were 48.6, 59.4, 68.4 and 61.3% respectively. Especially, at a concentration of 800$\mu\textrm{g}$/ml, the maturation rates(68.8%) of cumulus-removed oocytes were slightly lower than that(78.3%) of cumulus-enclosed oocytes. However, the treatment of hyaluronic acid showed significantly higher maturation rates compared to that(48.4%) of control group of cumulus-removed oocytes(p<0.05). Therefore, these results suggest thate hyaluronic acid had a beneficial effect on maturation of bovine follicular oocytes. 2. The maturation rate of cumulus-free oocytes treated with chondroitin sulfate(200, 400, 800 and 1, 600$\mu\textrm{g}$/ml) was 52.3, 56.1, 55.9 and 52.2% respectively. These rates were not different from those(52.9%) of control group. However, these rates in cumulus-free oocytes were significantly lower than that(79.0%) in cumulus-enclosed oocytes(p<0.01). Therefore, these results suggest that chondroitin sulfate do not affect on the maturation of oocytes. 3. In cumulus-free oocytes cultured with different heparin concentration, the maturation rates were ranged from 48.5 to 52.1%, showing no differencies from that(50.7%) of control group. However, these rates were significantly lower than 80.0% in cumulus-enlosed oocytes(p<0.01). 4. The nuclear maturaton of oocytes was increased by treatment of each of three glycosaminoglycans(hyaluronic acid, chondroitin sulfate, and heparin). In addition, the treatment of mixed together showed the significant additive effect. Hyaluronic acid was more effective than chondroitin sulfate and heparin were.

• Journal of Embryo Transfer
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• v.11 no.3
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• pp.241-248
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• 1996

This study was conducted to improve the production efficiency of in vitro produced (IVP) embryos in Korean Native cows. The optimal conditions and procedures for in vitro maturation(IVM), in vitro fertilization(IVF) and in vitro culture(IVC) of bovine follicular oocytes and IVP embryos were evaluated. Immature follicular oocytes were collected fiom the follicles of bovine ovaries obtained from abattoirs. The oocytes of Grade I and II for IVM were cocultured with monolayered bovine oviductal epithelial cells(BOEG) or granulosa cells in TCM-199 solution supplemented with follicle stimulating hormone, lutenizing hormone, estradiol-17$\beta$ and heat inactivated fetal calf serum at 39$^{\circ}C$ under 5% $CO_2$ in air for 14 to 24 hours. Most of the oocytes(93%) matured to metaphase II in 24 hours. The cocultured IVM oocytes were fertilized in vitro at significantly(P<0.05) higher rate with BOEC(83.8%) and with granulosa cells(84.6%) than the non-cocultured IVM oocytes(73.6%). The IVM-IVF embryos developed to morula and blastocyst at significantly(P<0.05) higher rate in coculture with BOEC(41.2%) than with granulosa cells(23.1%) or conditioned medium(23.4%).

• Korean Journal of Animal Reproduction
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• v.13 no.3
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• pp.171-178
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• 1989

These experiments were carried out to investigate the effect of a co-culture with granulosa cells on in vitro maturation, fertilization and development of bovine follicular oocytes. The bovine ovaries were obtained at a slaughter house and the follicular oocytes were recovered by aspirating the follicular fluid from the visible follicles of diameter 2-6mm. Bovine oocytes were matured in vitro for 24-26 hr and then fertilized in vitro using epididymal spermatozoa capacitated by preincubation for 2-3hr in BO solution containing BSA(5mg/ml) and caffein(25mM). Eight hours after insemination, the oocytes were cultured in a co-culture system with granulosa cells. The rates of maturation of the follicular oocytes cultured in a co-culture system with granulosa cells were 83.1%, the rate of fertilization of the follicular oocytes culture in a co-culture in a co-culture system with granulosa cells were 76.9%, respectively. No significant difference are observed between control and treatment in maturation and fertilization rates. The rates of embryos developed to 2-, 4-, 8-, 16-cell and monula stages after co-cultured with granulosa cells were 65.8, 57.9, 39.5, 34.2 and 34.2%, respectively. The value for 16-and morula stages were significantly higher (P<0.05) than those of the embryos cultured in the basic medium.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.1
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• pp.23-28
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• 2003

The present study was undertaken to investigate the effects of PVP concentration and exposure temperature to vitrification solution on the post-thaw survival, in vitro maturation and development of immature bovine oocytes (germinal vesicle stage). The vitrification solution (VS) consisted of 40% ethylene glycol (EG)+0.5 M sucrose (S)+10% FBS. PVP was added to VS: 0%, 5% or 10%. The cumulus-oocyte complexes (COCs) were diluted in VS as one step, after 2 min the COCs were loaded in straw and vitrified by direct immersion into liquid nitrogen. For thawing, the straws were plunged into $30^{\circ}C$ water bath for 10s. After thawing, the oocytes were diluted in 0.5 M (in DPBS with 10% FBS) sucrose solution for 5 min. The survival rate (FDA-test and trypan blue) of immature bovine oocytes was measured. The survival rate was higher in 5% PVP (91.5%) than in 0% (64.2%) or in 10% PVP (79.7%). The proportion of metaphase II formation was 69.35% in control (no vitrified COCs), 9.3% in 40% EG+0.5 M S+0% PVP and 21.05% in 40% EG+0.5 M S+5% PVP (p<0.05). The effect of room temperature ($25^{\circ}C$ for 10 min) and cold temperature ($4^{\circ}C$ for 10 min) on COCs were determined in this study. After IVF, the cleavage and blastocysts rate of oocytes exposed to room temperature and cold temperature in VS+5% PVP was significantly different (2 cell: 63.20% vs 37.97%, blastocysts: 18.40% vs 2.53%). The cleavage rates of frozen-thawed oocytes were 20.53% with PVP and 22.13% without PVP (p>0.05). Two out of 151 oocytes (1.32%) developed to blastocyst stage after frozen-thawed with 5% PVP (p>0.05). Development of oocytes after frozen-thawing to the 2 cell were not significantly affected with or without PVP following IVF. However, the vitrification of immature bovine oocytes with PVP maintained the ability to develop to the blastocyst stage after IVM-IVF and IVC, while no blastocysts were obtained from oocytes vitrified without PVP. These results suggested that PVP has a protective role for vitrification of immature bovine oocytes as far as survival is concerned, however, the protection was not sufficient enough to support blastocyst formation.

• Korean Journal of Animal Reproduction
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• v.12 no.2
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• pp.112-119
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• 1988

These studies were conducted to investigate the effects of culture temperature and time on the in vitro maturation and semen type and media on the in vitro fertilization of bovine follicular oocytes, and to asses in vitro fertilization rate of oocytes cultured by extraffollicular method following fertilization in vitro, or transfer into the pseudopregnant rabbit oviduct or uterus. The bovine oocytes recovered from follicles were cultrued for 18 hrs or 72hrs at 38$^{\circ}C$ with 5% CO2 in moist air. Flesh-diluted(2 folds) and frozen-thawed semen in 0.5ml straw from a fertile bull were used. In order to obtain capacitation of spermatozoa were treated with bovine follicular fluids(BFF) and Inophore A(IA). The results obtained were summarized as follows: 1. The oocytes were classified as "A, B, C, D and Degenerative" depending morphological integrity and those were 62.0%, 12.0%, 17.2%, 5.9% and 3.0% of the total oocytes harvested, respectively. 2. The oocytes matured to metaphase II were significantly increased between 24-48hrs of incubation and at 37-39$^{\circ}C$ with 5% CO2 in moist air. 3. The in vitro fertilization rate following transferred into rabbit oviduct or uterus with bull semen and in vitro matured oocytes were higher ligation than non-ligation of oviduct or uterus. 4. The in vitro fertilization rate of oocytes matured in vitro were higher neat than frozen semen and treatment of IA than BFF on the capacitation of spermatozoa. 5. The effects of semen types and media on in vitro fertilization of oocytes matured in vitro were higher fertilization rate of neat than friozen semen, and media was not significant.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.2
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• pp.151-156
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• 1991

Bovine in vitro fertilization experiment was carried out using ovary-derived follicular oocytes and frozen-thawed spermatozoa to determine the optimal preincubation time of spermatozoa and the insemination time for successful in vitro fertilization rate. The possibility of parthenogenetic cell division of unfertilized oocytes during culture without spermatozoa was also examined. There was no significant (p>0.05) difference in percent ratio of embryos developed to blastocyst stage between 0 and 3 h preincubation times of spermatozoa, showing a tendency to have higher percentage for 0 h of preincubation time. The 6 h insemination time seemed to be better for producing higher percentage of ova cleavage compared with those of 1 and 3 h treatments. Approximately 10% of unfertilized oocytes divided into 2 to 4-cell stage, and some of them cleaved to 5 up to 8-cells. The results obtained from this study suggested that 0 h of sperm preincubation time and 6 h of insemination time would be suitable for producing better in vitro fertilization rate of bovine oocytes. It is also likely that unfertilized bovine oocytes probably cleave to some cell stages with irregular divisions of the cells. On the one hand, considerable variation was also found in spermatozoa function among individual bulls.

• Journal of Embryo Transfer
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• v.12 no.1
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• pp.27-36
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• 1997

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 $\beta$-estradiol and 10% FCS for 24~48 hrs in incubator with 5% $CO_2$ in air at 38.5$^{\circ}C$. The bovine embryos following dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquld nitrogen and thawed in 3$0^{\circ}C$ 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$\times$ 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+$\beta$-estradiol, hCG+$\beta$-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$0^{\circ}C$ after rapid freezing of bovine embryos resulted in a significantly higher embryos survival rate than did at 2$0^{\circ}C$ and 35$^{\circ}C$.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)

• Korean Journal of Animal Reproduction
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• v.21 no.1
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• pp.71-78
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• 1997

This study was conducted to investigate the activation condition of freshly matured bovine IVM oocytes for use as a cytoplasmic recipient in nuclear transfer. Bovine oocytes matured in vitro for 22-24 h were treated with various activation conditions. In Experiment 1 in vitro matured oocytes were treated with electric stimuIus (ES; 2 pulses of 1.25 kV/cm for 70 ${\mu}{\textrm{s}}$ec, each pulse 1 sec apart), ethanol (ET; 7%, 5min) , Ca$^2+$-ionophore(A23187; 10$\mu\textrm{g}$/ml, 5min) and cycloheximide(CH; 10$\mu\textrm{g}$/ml, 6 h). Activation rates were similar in treatments with ES, ET and A23187(48.8~54.3%), however, significantly reduced with CH treatment(15.9%, P