• Clinical and Experimental Reproductive Medicine
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• v.47 no.2
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• pp.140-146
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• 2020

Objective: To investigate whether the degree of post-warming embryo or blastocyst development is associated with clinical pregnancy in vitrified embryo or blastocyst transfer cycles. Methods: Ninety-six vitrified cleavage-stage embryos and 58 vitrified blastocyst transfer cycles were selected. All transfer cycles were performed from February 2011 to March 2019, and all vitrified embryos or blastocysts were warmed from 4 PM to 6 PM and then transferred the next morning from 9 AM to 10 AM. The scores of the cleavage-stage embryos and blastocysts were assessed at warming and at transfer using the modified Steer method and the Gardner method, respectively. The mean embryo or blastocyst score, score of the single top-quality embryo or blastocyst, and the difference in the score between warming and transfer were compared between nonpregnant and pregnant women. Results: In the cleavage-stage embryo transfer cycles, both the top-quality embryo score at transfer and the difference in the score between warming and transfer were significantly associated with clinical pregnancy. A top-quality embryo score at transfer of ≥ 60.0 (area under the curve [AUC], 0.673; 95% confidence interval [CI], 0.531-0.815) and a difference in the score between warming and transfer of ≥ 23.0 (AUC, 0.675; 95% CI, 0.514-0.835) were significant predictors of clinical pregnancy. In blastocyst transfer cycles, the top-quality blastocyst score at transfer was the only significant factor associated with clinical pregnancy. A top-quality blastocyst score at transfer of ≥ 38.3 was a significant predictor of clinical pregnancy (AUC, 0.666; 95% CI, 0.525-0.807). Conclusion: The top-quality embryo score at transfer and the degree of post-warming embryo development were associated with clinical pregnancy in vitrified cleavage-stage embryo transfer cycles. In vitrified blastocyst transfer cycles, the top-quality blastocyst score at transfer was the only significant factor affecting clinical pregnancy.

• Clinical and Experimental Reproductive Medicine
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• v.39 no.3
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• pp.114-117
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• 2012

Objective: It is well known that fresh blastocyst transfer results in better pregnancy outcomes with a smaller number of transferred embryos compared with cleavage stage embryo transfer. However, in terms of frozen-thawed blastocyst transfer, only a few studies are available. We aimed to evaluate clinical outcomes of frozen-thawed embryo transfer (FET) with blastocysts. Methods: Retrospective analysis of FET cycles with blastocysts (B-FET) between Jan 2007 and June 2009 was performed. Age-matched FET cycles with cleavage stage embryos (C-FET) during the same period were collected as controls. A total of 58 B-FET cycles were compared with 172 C-FET cycles and also compared with those of post-thaw extended culture blastocysts from frozen pronuclear stage embryos (22 cycles). Results: There was no difference in the patient characteristics of each group. The embryos' survival rates after thawing were comparable (>90%) and there was no difference in the implantation rate or clinical and ongoing pregnancy rate among the three groups. Conclusion: In FET, blastocyst transfers may not present better pregnancy outcomes than cleavage stage embryo transfers. A further large-scale prospective study is needed.

• Korean Journal of Animal Reproduction
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• v.22 no.2
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• pp.153-161
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• 1998

This study was conducted to examine the viability of nuclear transfer bovine embryos following embryo transfer. Donor embryos were treated with nocodazole to arrest their cell-cycle-stage at mitotic(M) phase. After releasing from nocodazole blastomeres were separated and transferred into the enucleated oocytes(BC), or cultured in medium with aphidicolin. Freshly cleaved blastomeres within 1.5h after cleavage(AC) and non-cleaved ones up to 3h after releasing from nocodazole(NC) were transferred into the enucleated oocytes. Blastocysts derived from nuclear transfer were transferred to Day 7~8 recipient cows. Some blastocysts were vitrified and thawed before embryo transfer. Developmental rates to the blastocyst stage were higher in AC(18.1%, P<0.05) than BC(8.6%) and NC(5.1%). Blastocyst development slightly enhanced with aphidicolin(1~2$\mu\textrm{g}$/ml) treatment(16.9~22.6%) compared to non treated control(11.1%). Survival rate fo vitrified nuclear transfer embryos after thawing was 75%(24/32). Twnety-three vitrified nuclear transfer embryos and 3 fresh ones were transferred to 23 recipients, 6 heads were pregnant and 1 male calf(24 kg) was born from a recipient cow recevied one vitrifiedthawed nuclear transfer embryo at 277 days after embryo transfer. This result suggests that the nuclear transfer embryos can developed to term after vitrification andembryo transfer.

• Journal of Embryo Transfer
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• v.15 no.2
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• pp.129-136
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• 2000

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 $\mu$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.

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.151-159
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• 1997

In vitro fertilization(IVF) derived morula and blastocyst embryos were bisected by a simple method and cultured in vitro without zona pellucida And also bisected embryos were frozen-thawed and cultured in vitro) to evaluate the survival rate. The results obtained were as follows : The average number of grade I or II immature follicular oocytes recovered by slicing method per ovary was 11.9 from 142 ovaries. Following in vitro fertilization, the rates of cleavage and in vitro development to morula and blatocyst were 61.7 and 32.2% respectively. The successful bisection rate of IVE embryos was 67.51%, and the embryos of blastocyst stage were bisected successfully at significantly(P

• Journal of Embryo Transfer
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• v.14 no.1
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• pp.23-29
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• 1999

The objectives of the study were to establish sperm separation method and duration of insemination for bovine IVF. Oocytes from slaughterhouse ovaries were matured and fertilized using general protocol. After 18 or 42 h of insemination, six to ten embryos were placed into a 30${mu}ell$ drop of each medium, and the embryos were examined 7~10d post in semination without medium renewal. First, we compared Percoll gradient will swim-up technique for sperm separation. There was no difference in cleavage rates between them, but the development rates over morula stage of oocytes fertilized with sperm separated by Percoll gradient was significantly higher than that sperm selected by swim-up technique (p<0.05). Second, we evaluated development of bovine embryos derived from the IVF procedure with different durations(18 vs 42 h) of fertilization. There was also no difference in cleavage rates, but the development to blastocyst stage of oocytes exposed in cleavage rates, but the development to blastocyst stage of oocytes exposed to sperm for 42 h was significantly higher than that exposed for 18 h (p<0.05). In conclusion, Percoll gradient can be used for sperm selecton, improving of embryonic development. Also, 42h of IVF may improve the development of bovine embryos.

• 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.

• Clinical and Experimental Reproductive Medicine
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• v.50 no.3
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• pp.177-184
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• 2023

Objective: Reconstructed oocytes after polar body genome transfer constitute a potential therapeutic option for patients with a history of embryo fragmentation and advanced maternal age. However, the rescue of genetic material from the first polar body (PB1) through introduction into the donor cytoplasm is not yet ready for clinical application. Methods: Eighty-five oocytes were obtained following in vitro maturation (IVM) and divided into two groups: PB1 nuclear transfer (PB1NT; n=54) and control (n=31). Following enucleation and PB1 genomic transfer, PB1 fusion was assessed. Subsequently, all fused oocytes underwent intracytoplasmic sperm injection (ICSI) and were cultured in an incubator under a time-lapse monitoring system to evaluate fertilization, embryonic morphokinetic parameters, and cleavage patterns. Results: Following enucleation and fusion, 77.14% of oocytes survived, and 92.59% of polar bodies (PBs) fused. However, the normal fertilization rate was lower in the PB1NT group than in the control group (56.41% vs. 92%, p=0.002). No significant differences were observed in embryo kinetics between the groups, but a significant difference was detected in embryo developmental arrest after the four-cell stage, along with abnormal cleavage division in the PB1NT group. This was followed by significant between-group differences in the implantation potential rate and euploidy status. Most embryos in the PB1NT group had at least one abnormal cleavage division (93.3%, p=0.001). Conclusion: Fresh PB1NT oocytes successfully produced normal zygotes following PB fusion and ICSI in IVM oocytes. However, this was accompanied by low efficiency in developing into cleavage embryos, along with an increase in abnormal cleavage patterns.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.1
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• pp.53-60
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• 2011

Objective: This study was carried out to compare the clinical outcome of elective single cleavage-embryo transfer (eSCET) to that of elective single blastocyst-embryo transfer (eSBET) in human IVF-ET. Methods: This study was a retrospective study which analyzed for 614 women who visited the Daegu Maria Clinic from August 2008 to December 2009. All were under 37 years old and had more than 8 mm of endometrial thickness on the day of hCG administration and at least one good quality embryo on day 3. The eSCETs were performed on day 3 (n=450) and the eSBETs were conducted on day 5 (n=164). Results: The numbers of retrieved oocytes, fertilized oocytes, and day 3 good quality embryos were significantly lower in the eSCET group (12.1${\pm}$6.0, 8.2${\pm}$4.6, and 4.2${\pm}$3.1, respectively) compared to the eSBET group (16.7${\pm}$7.2, 12.1${\pm}$5.0, and 8.5${\pm}$4.5, respectively; p<0.001). However, the clinical pregnancy, implantation, on-going pregnancy, and live birth rates of the eSCET group (46.7, 46.9, 40.0, and 36.7%, respectively) were not statistically different from those of the eSBET group (51.2, 51.8, 45.1, and 43.9%, respectively; p=0.318, 0.278, 0.254, and 0.103, respectively). Conclusion: These results suggested that elective single embryo transfer should be performed regardless of the developmental stage to women less than 37 years old who had more than 8 mm of endometrial thickness on the hCG administration day and at least one good quality embryo on day 3 in order to reduce the twin pregnancy rate without reducing the whole pregnancy rate.

• Journal of Embryo Transfer
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• v.14 no.2
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• pp.93-97
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• 1999

The development potential of bovine somatic cells was evaluated using nuclear transfer. A single donor cell derived from fetus of HanWoo(Korean Native Cattle) was selected and deposited into perivitelline space of each enucleated oocyte before electrical fusion and activation. Nuclei of donor cells starved for 7 days (37%) tended to support the development of reconstitute embryo the blastocyst stage better than those of donor cells starved 3, 14 and 30 days. The cleavage rate was significantly lower(P<0.05) in reconstitute embryos derived from large size donor cells(51.2%), than those from small medium size donor cells(76.6 and 73.5, respectively). The developmental rate to blastocyst of reconstructed embryos from medium size donor cells was higher than those from small and medium size donor cells. This study demonstrates that an appropriate culture period for induction into quiescent stage and the size of donor cells effect on the efficiency of nuclear transfer using cultured bovine cells.