• Journal of Embryo Transfer
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• v.9 no.1
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• pp.7-14
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• 1994

The present experiments on cryopreservation were designed to examine the effects of solution toxicity, equilibration time and cell stages on the post-thaw survival of bovine IVF embryos. The oocytes were matured in vitro(IVM) for 24 hrs. in TCM-199 supplemented with 35 $\mu$g /ml FSH, 10 $\mu$g /ml LH, 1 $\mu$g /ml estradiol-17$\beta$ and granulosa cells at 39$^{\circ}C$ under 5% $CO_2$ in air. They were fertilized in vitro(IVF) by epididymal spermatozoa treated with heparin for 24 hrs., and then the zygotes were co-cultured in vitro(IVC) with bovine oviductal epithelial cells for 7 to 9 days. The bovine IVF embryos were exposed to the EFS solution in one step at room temperature, kept in the EFS solution during different period for toxicity test, vitrified in liquid nitrogen, and thawed rapidly. 1. after the bovine blastocysts were exposed to EFS solution for 2 min. at room temperature and then they were washed in 0.5 M sucrose solution and TCM-199, they were cultured to examined cryoprotectant induced injury during exposure, Most of the embryos(95.0%) developed to reexpanded blastocoels. However, when the exposure time was extended to 5 and 10 min, these development rates dropped dramatically in 5 min. (69.5%) and 10 min. (47.4%), respectively, 2. When the bovine IVF embryos were vitrified in EFS solution after the equilibration for 1 and 2 min. exposure, The embryos to have reexpanded blastocoels following thawing, washing and culture processes were found to he 82.6 and 73.9%, respectively. However, when the exposure time was extended to 3 min, this survival rate dropped to 18.2%. The optimal time for equilibration of bovine IVF blastocysts in EFS solution seemed to he 1~2 min. 3. When the bovine IVF embryos were equilibrated for 1 min. the significantly (P<0. 05) higher post-thaw survival rates were obtained from the embryos of blastocyst stage(81.3%) than morulae stage(5. 1%). The optimal cell stage for viterification with EFS solution proven to he blastocyst stage in bovine IVF embryos. 4. The number of blastomeres of blastocyst stage was examined with nuclear staining with Hoechst 33342 during 7 to 9 days post-insemination. The cell counts of frozen bovine IVF embryos were found significantly(P$\geq$7.5 and those of the fresh embryos 76.6$\geq$7. 1, which were cultured in the sarne period and conditions as frozen embryos.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.275-280
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• 1997

This study was carried out to investigate on the survival and in vitro developmental rates of bisected bovine embryos by microblade, micropipette and pronase methods. Bisected embryos cultured for 1∼7 days in TCM-199 media with 10 FCS＋hormones. Survival and in vitro developmental rates was defined on in vitro culture or FDA-test. The results are summarized as follows ; 1. The survival and in vitro developmental rates of bisected bovine embryos by microblade, micropipette and pronase methods were 22.2, 16.7, 15.0% and 22.2, 23.3, 18.8%, respectively. In vitro developmental rate of bisected bovine embryos was significantly lower than that of non-bisection embryos(27.8% and 25.0%). 2. In vitro developmental rates of bovine embryos bisected for 1, 2, 4, 8, 16 cells stages during in vitro culture in 10% FCS＋TCM-199 media were 25.0, 20.0, 20.0, 15.0 and 6.7%, respectively. 3. In vitro developmental rates of intact and free-zona pellucida of bisected demi-embryos during in vitro culture in 10% FCS＋TCM-199 media were 25.6, 16.7%, respectively. 4. In vitro developmental rates of biopsied embryos and biopsied blastomeres during in vitro culture in 10% FCS＋TCM-199 media were 20.0, 11.1%, respectively.

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.161-169
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• 1997

This study was conducted to compare the insemination time of bovine oocytes and determine the effects of glucose(1.5 mM) on the development of bovine embryos at early cleavage stage. Oocytes were matured for 24 h, followed by exposure to sperm and cultured in modified Tyrode's media drops or with bovine oviduct epithelial cell monolayer prepared in TCM199(BOECM). Insemination time and culture system were varied in each experiment. In experiment 1, to investigate the developmental capacity of bovine embryos after different time of exposure to sperm, bovine ova and sperm were co-incubated for 18, 30 or 54 h, respectively. The development to blastocysts of 30 and 54 h insemination groups were significantly higher(P<0.05) than 18 h group, and in case of blastocysts of cleaved embryos, 30 h group were significantly higher(P<0.05) than other groups. In experiment 2, we investigated the effect of glucose on early bovine embryos. After 18 h insemination, in vitro fertilized oocytes were separated following 3 groups ; G+0, C+24 and C+48. Oocytes of G+0 group were cultured in glucose added Tyrode's medium after fertilization, oocytes in C+24 and C+48 groups were cultured in glucose free Tyrode's medium after fertilization. After 24 h culture, G+24 group was moved to glucose added medium. All oocytes of 3 groups were moved to BOECM after 48 h culture. The rates of cleavage and development to blastocysts in G+0 group were significantly lower than other groups. In experiment 3, we determined the effects of glucose exposure from 8 to 20 h after insemination on the cleavage and development of oocytes. The oocytes in glucose added group had high capacity of cleavage and further development. This study shows that in bovine oocytes, the optimal exposure to sperm is 30 h and glucose exposure to bovine one-cell embryos is detrimental to their first cleavage and further development in vitro but there has no evidence of detrimental effect of glucose(1.5 mM) exposure to bovine embryos over the two-cell stage in vitro.

• Korean Journal of Animal Reproduction
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• v.21 no.2
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• pp.103-109
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• 1997

The studies on the carried out to investigate to determine the optimum thawing temperature and equilibration time and 1 step straw method of frozen bovine embryos. The follicular oocytes were cultured in TCM-199 medium containing 10 IU/ml PMSG(Sigma, USA), 10 IU/ml hCG(Sigma, USA), 1 $\mu\textrm{g}$/ml $\beta$-estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% CO2 in air at 38.5$^{\circ}C$ and then matured oocytes were again cultured for 12~18 hrs with motile capacitated sperm by preincubation of heparin. The bovine embryos following dehydration by cryoprotective agents and various concentration of sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water. Survival and in vitro developmental rate was defined as developmental rate on in vitro culture or FDA-test. The results are summarized as followes : 1. The equilibration time on in vitro developmental 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 (10~20 min.). 2. The temperature thawed at 3$0^{\circ}C$ after rapid freezing of bovine embryos resulted in a significantly higher in vitro developmental rate than did at 2$0^{\circ}C$ and 35$^{\circ}C$. 3. The thawing time on in vitro developmental rates of bovine embryos was attained after short period of time(1~5 min.) in the freezing mediuim higher than long period of time(10min.). 4. The in vitro developmental rates of bovine embryos after rapid frozen-thawing by 1 step straw method in the freezing medium added 1.5M, 2.0M glycerol, DMSO, propanediol and 0.25M, 0.50M, 0.75M, 1.00M sucrose were 12.5~19.4%, 10.0~15.6%, 9.1~13.8% and 6.7~12.9%, respectively.

• Korean Journal of Animal Reproduction
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• v.18 no.4
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• pp.275-284
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• 1995

In sexing early mammalian embryos, viability of biopsied embryos and accuracy of sexing are both important. We have been previously developed efficient methods for biopsy of mouse embryos and sex identification from a single blastomere by PCR. In this study, squeeze method used for biopsy of mouse embryos was applied to bovine embryos. Compact bovine morulae were obtained by flushing uteri on Day 6 after the onset of standing estrus. A small number of blastomeres could be isolated from bovine morulae by the biopsy method. All 13 biopsied morulae were survived and 10 embryos developed to normal blastocyst after 24 h of culture. Subsequently, sex of the bovien embryos was identified from a few blastomeres by PCR amplifying a Y-specific bovine DNA sequence. Among 13 embryos analyzed, 7 embryos were determined as males and 6 embryos as females. Thus, bovine embryos at morular stage could be successfully biopsied by the squeeze method and sex of the bovine embryos determined from biopsied material by PCR.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.5
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• pp.498-502
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• 1998

The present study was designed, fIrst to develop the new methodology to measure the bioluminescence activity easily in live developing bovine embryos by photoncounting, and secondly to compare the expression efficiency of four luciferase reporter genes in bovine embryos at four- to 16-cell stages. In experiment 1, equimolar pSVlacZ and pSVEluc were microinjected into the pronucleus of fertilized bovine oocytes. At 2 days after micro injection, bioluminescence activity of these embryos was measured by photoncounting with a luminometer for 1 min, and lacZ gene expression in the same embryos was assayed by X-gal staining. All the luciferase-positive oocytes showed some bacterial ${\beta}$-galactosidase activity irrespective of the intensity. In experiment 2, four firefly luciferase genes (pTKEluc, pTK6WEluc, pSVEluc and pMiwluc) were introduced by micro injection, and the injected embryos were cultured for the following 2 days. Detection of the luciferase gene expression was done by photoncounting at 5 to 55 min. Over the measurement period, the luciferase activity was almost constant irrespective of the transgenes microinjected. The luciferase activity and expression efficiency at 2 days after microinjection were not significantly affected by the difference in the microinjected transgenes. The present results demonstrated that the bioluminescence activity in live developing bovine embryos could be measured quickly by photoncounting.

• Korean Journal of Veterinary Research
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• v.35 no.1
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• pp.187-195
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• 1995

The present study carried out to determine the developmental capacity of bovine oocytes matured in epidermal growth factor(EGF)-containing medium, the developmental competence of bovine embryos using synthetic oviduct fluid(SOF) and the effect of glucose on the development of bovine embryos. In experiment 1, oocytes, obtained from abattoir ovaries, were matured in EGF-containing medium for 24 hours, followed by exposure to Korean native cattle spermatozoa for 18 hours and cultured by utilizing co-culture system with bovine oviduct epithelial cells(BOEC) in TCM199. In experiment 2, early bovine embryos were cultured in SOF with or without BOEC and compared with those in TCM199 with BOEC. In experiment 3, bovine embryos were cultured in the presence or absence of glucose. Seven and ten days after in vitro fertilization, developmental competence of embryos were evaluated. The rate of cleavage was significantly(P<0.05) higher in EGF-containing maturation medium(70.0%) than in control(57.7%). The rates of development to morulae and blastocysts were 30.6% and 23.3% there was no significant difference between them. The rates of in vitro fertilized embryos to morulae and blastocysts cultured in SOF with BOEC(30.4%) and in TCM199 with BOEC(38.0%) were significantly(P<0.01) higher than cultured in SOF without BOEC(13.4%) at seven days after in vitro fertilization. The rates of embryos to blastocysts cultured in SOF with BOEC(29.4%) and in TCM199 with BOEC(35.9%) were significantly(P<0.05) higher than cultured in SOF without BOEC(13.4%) at ten days after in vitro fertilization. The rates of early embryos to morulae and blastocysts cultured in the presence or absence of glucose were 12.2% and 17.5% each other, there was no significant difference between them. The results show that bovine oocytes matured in the presence of EGF can cleave better, SOF with BOEC can replace serum containing complex media, TCM199 with BOEC in bovine embryo culture and glucose have little effect on the culture of early bovine embryos.

• Korean Journal of Animal Reproduction
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• v.18 no.4
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• pp.251-256
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• 1995

Two experiments were conducted to study the production of in vitro fertilized bovine embryos and the viability of blastocysts cryopreserved by vitrification. In experiment 1, production rate of in vitro matured bovine oocytes after fertilization in medium containing bovine oviduct epithelial cells (BOEC), cumulus cells and granulosa cells to blastocysts were 18.4, 14.6 and 13.1%, respectively. Developmental percentages of blastocysts produced at day 6, 7 and 8 were 8.5, 10.6 and 15.2% respectively. Hatching rate of bovine embryos produced was 60.0%. In experiment 2, post-thawed surviving embryos in a vitrification solution consisting of 7.15M ethylene glycol, 2.5 mM ficoll and 0.3 M sucrose were 36.4% (56/154). Also, survival rate of bovine embryos after exposed to vitrification solution at 1, 2, 3, 4 and 5 min were 84.0, 88.0, 71.0, 48.0 and 24.0% respectively.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.92-92
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• 2003

Accurate analysis of nuclear status is needed when biopsied-blastomeres are used for embryo sexing. In this study, the nuclear status of blastomeres derived from 8- to 16-cell stage IVF bovine embryos was analyzed to evaluate the representative of single blastomere for embryo sexing. When 55 embryos were analyzed by PCR following biopsy, the coincident rate of sex determination between biopsied-single blastomere and matched blastocyst by PCR was 80 %. Karyotyping of biastomeres in 8- 16-cell stage bovine embryos was conducted to assess chromosome status of IVF embryos. To establish karyotyping of blastomeres, concentrations of vinblastine sulfate and duration of exposure time for metaphase plate induction with 8- to 16-cell stage bovine embryos were tested. The most effective condition for induction of metaphase plate (>45%) was 1.0 ug/ml vinblastine sulfate treatment for 15 h. In 22 embryos under the condition, only 8 embryos out of ten that had a normal diploid chromosome complement showed a sex-chromosomal composition of XX or XY (36.4%) and 2 diploid embryos showed mosaicism of the opposite sex of XX and XY in blastomeres of embryo (9.1%). One haploid embryo contained only one X-chromosome (4.5%). Four out of the other 11 embryos having a mixoploid chromosomal complement contained haploid blastomere with wrong sex chromosome (18.2%). These results suggested that morphologically normal bovine embryos derived from IVF had considerable proportion of mixoploid and sex-chromosomal mosaicism which could be the cause of discrepancies of the sex between biopsied-single blastomere and matched blastocyst by PCR analysis.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.4
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• pp.595-598
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• 1989

Bovine embryos/ova obtained from in-vitro fertilization were either co-cultured on a monolayer of bovine cumulus cells or cultured in medium alone. Embryos/ova co-cultured with cumulus cells developed to 8-cell (30.9%), morula (29.8%) and blastocyst stages (26.6%) after 3-4, 5-6, and 7-8 days of culture, respectively, while embryos/ova cultured in medium alone failed to develop beyond 8-cell (0-13.3%), morula (0-1.5%) and blastocyst stages (0%). The results of this study demonstrated the beneficial effect of cumulus cells on the development of bovine embryos.