• Journal of Embryo Transfer
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• v.8 no.1
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• pp.37-44
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• 1993

Nuclear transplantation techinque has been found to be the most potential and efficient method for producing a large number of genetically identical animals from a single embryo. The technical development of nuclear transplantation in mammals and its application to the production of cloned animals were reviewed. For the efficient and successful production of cloned embryos by nuclear transplantation, selection and micromanipulation of recipient eggs or embryos as capacious recipient cytoplasm, and benefitial preparation of multiple totipotent embryonic cells as donor nuclei, and also fusion technique are very critical. Recent works approaching to these critical points were introduced and discussed.

• Journal of Embryo Transfer
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• v.14 no.3
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• pp.171-176
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• 1999

This study was carried out to investigate the effect of co-culture system(bovine oviduct epithelial cells; BOEC) and defined culture system (modified TALP ; mTALP) on the conception of embryos transferred, and pregnancy and twin birth rates after transfer of fresh or frozen-thawed bovine blastocysts produced in vitro were also evaluated. Oocytes from the slaughterhouse ovaries were matured and fertilized using general protocol. The results obtained were as the following. The pregnancy rate after transfer was higher in co-culture group than in mTALP group, but was not signficantly different, and there is no difference between fresh embryo group and frozen-thawed embryo group in conception rate. The conception rate was not different whether 3∼4 blastocysts or 2 blatocysts transferred into a recipient, but the production rate of twin calves was significantly higher (p<0.05) when 3∼4 embryos transferred. The average birth weight of twin calves(24.38kg) was numerically, but not significantly lighter than that of single calves(26.68kg).

• Clinical and Experimental Reproductive Medicine
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• v.37 no.4
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• pp.349-359
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• 2010

Objective: This study was performed to compare the clinical outcome of elective single embryo transfer (eSET) performed at the cleavage stage to that of elective double embryo transfer (eDET). Methods: Of the women less than 36 years old who visited Daegu Maria from January 2008 to April 2009, the only women (n=330) with more than 8 mm of endometrial thickness and at least one good quality embryo, who were treated with GnRH agonist long protocol, were included in this study. After information about complications that can arise by multiple embryo transfer, either eSET or eDET was conducted by their request (167 and 163, respectively).Results: The implantation rate of eSET group was significantly higher than that of eDET group (53.9% vs. 40.2%, p<0.01). The twin pregnancy rate of eSET group was significantly lower than that of eDET group (1.1% vs. 32.3%, p<0.001). However, there were no significant differences between two groups in the clinical pregnancy (53.3% vs. 60.7%, p=0.172), ongoing pregnancy (47.3% vs. 54.6%, p=0.185) and live birth rates (44.9% vs. 50.9%, p=0.275). The number of the surplus embryos which developed to the blastocyst stage and cryopreserved at that stage was significantly higher in eSET group than that of eDET group ($3.2{\pm}2.6$ vs. $2.1{\pm}2.4$, p<0.001). Conclusion: These results suggest that eSET should reduce significantly the multiple baby pregnancy without decreasing the whole pregnancy rate in women with less than 36 years old.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.341-346
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• 2006

Despite many studies, results of superovulation protocols are not consistent in farm animals. In this study, 151 Boer goats were superovulated to examine the factors affecting superovulation and embryo transfer (MOET). An optimal regime for superovulation treatment was identified as a 4-day treatment with decreasing dosages of 6-7 mg Chinese FSH or 240 mg Canadian FSH. The 4-day treatment with decreasing dosages of 6-7 mg Chinese FSH was, therefore, adopted to study effects of the age of does, season and repeated treatments on superovulation and embryo transfer. The best season for superovulation and embryo transfer and pregnancy was autumn, and the best age range was 12-35 months old. Within animals there were no significant differences in the number of ovulations and the rate of transferable embryos between the first and the second superovulation. However, these parameters declined significantly for the third superovulation. No marked effects of the number of ovulations on the proportion of transferable embryos were noted. The parturition rate of the recipients receiving single embryos was not different significantly from those receiving two embryos, and the kidding rate calculated from embryos transferred did not differ significantly between recipients receiving one and two embryos.

• Clinical and Experimental Reproductive Medicine
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• v.42 no.4
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• pp.169-174
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• 2015

Objective: To assess compliance with Korean guidelines for embryo transfer, the possible reasons for non-compliance, and multiple pregnancies according to each specific condition in compliant cycles. Methods: A single-institution, retrospective study was conducted of 256 fresh in vitro fertilization cycles during 2012-2014. To assess compliance with Korean guidelines, the maximum recommended number of embryos transferred (according to criteria of age, transfer day, and presence of favorable conditions) was compared with the actual number of embryos transferred. Clinical pregnancy rate (PR) was assessed as the percentage of pregnant women resulting from each set of transfer conditions, including the number of embryos transferred. The multiple pregnancy rate (MPR) was calculated as the percentage of pregnant women with a multifetal pregnancy. Results: The compliance rate with the Korean guidelines was 96.5% (247/256). Non-compliance occurred in nine cycles owing to poor embryo quality, repeated implantation failure, or hostile endometrium. In compliant cycles, the PR was 31.2% (77/247), and the MPR was 27.3% (21/77; 20 twins and one triplet). Higher MPR was noted in two types of transfer conditions: transfer of three cleavage embryos in women aged 35-39 years with favorable conditions (66.7%; primarily from those aged 35-37 years) and transfer of two blastocysts in women aged ${\geq}40$ years with favorable conditions (50%). Conclusion: Under the Korean guidelines, compliance rate was high in our center. Multiple pregnancies occurred primarily in group with favorable conditions. In high-risk groups for multiple pregnancies, reducing number of embryos transferred should be considered than suggested in the guideline.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.116-116
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• 2002

Further development of reconstructed embryos may be dependent upon the synchronization of donor nucleus and recipient cytoplasm at cell fusion, To control the synchronization of donor and recipient cells, the enucleated MII arrested oocytes are artificially stimulated prior to embryo reconstruction. Destruction of cyclin B results in the exit of cells from M-phase of cell cycle. This study was designed to investigate the effects of single or combined stimulation affected cyclin B1 mRNA and protein levels in mouse oocytes. The oocyte activation was induced by 7% ethanol or 10$\mu\textrm{g}$/$m\ell$ Ca-ionophore without (single) or with (combined) 10$\mu\textrm{g}$/$m\ell$ cycloheximide. Competitive quantitative PCR for cyclin Bl mRNA and western blot analysis for cyclin B1 protein was preformed in mouse oocytes. Cyclin B1 mRNA level was significantly reduced in single (P<0.05) and combined (P<0.05) stimulation groups. However, this level did not change in non-activated group and increased in intact group. Cyclin B1 protein level was also significantly reduced in both single (P<0.05) and combined (P<0.05) stimulation groups. In conclusion, single and combined stimulation induces the degradation of cyclin B1 mRNA and protein after activation in enucleated mouse oocytes.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.115-115
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• 2002

To evaluate the correlations between the expression of cyclin B1 mRNA and protein after stimulation and oocyte activation and development of nuclear transferred mouse embryos, this study was performed. The oocyte activation was induced by 7% ethanol or 10$\mu\textrm{g}$/$m\ell$ Ca-ionophore without (single) or with (combined) 10$\mu\textrm{g}$/$m\ell$ cycloheximide (CH). Cyclin B1 mRNA and protein in mouse oocytes was evaluated by PCR and western blot. The activation and blastocyst development in both single (P<0.05) and combined (P<0.01) stimulation was higher than in non-activated group. The cyclin B1 mRNA and protein levels were significantly reduced in both single and combined stimulation groups (P<0.05), respectively. Cyclin B1 mRNA expression showed a negative correlation between activation and blastocyst development in both single and combined stimulation groups. And also the expression of cyclin B1 protein showed a negative correlation with between oocyte activation and blastocysts development in both single and combined stimulation groups. In conclusion, it may suggest that single and combined stimulation increases the oocyte activation and blastocyst development of nuclear transferred embryos, because it induces the degradation of cyclin B1 mRNA and protein after activation in enucleated mouse oocytes.

• Clinical and Experimental Reproductive Medicine
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• v.51 no.1
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• pp.85-90
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• 2024

Objective: The purpose of this study was to compare fresh and frozen-thawed euploid blastocyst transfer protocols following preimplantation genetic screening (PGS) in cases of advanced maternal age. Methods: A total of 330 patients were examined retrospectively. PGS was performed on the embryos of 146 patients for whom fresh transfers were chosen. In contrast, frozen-thawed euploid single embryo transfer (ET) was selected after PGS for 184 patients, and their embryos were vitrified. The percentage of euploid embryos and rates of implantation, pregnancy, and pregnancy continuity, as well as clinical and biochemical abortion rates, were compared. Results: The numbers of retrieved oocytes, metaphase II oocytes, and fertilized ova were greater in the frozen-thawed group. The percentages of euploid embryos were comparable between the fresh and frozen-thawed groups (32% vs. 34.8%, respectively). The rates of implantation (46.6%vs. 62.5%), pregnancy (50% vs. 66.8%), ongoing pregnancy (38.4% vs. 53.8%), and live birth percentage (37.0% vs. 53.8%) were significantly higher in the frozen-thawed group. However, no significant differences were found in the clinical and biochemical abortion rates. Conclusion: The use of frozen-thawed single euploid ET is associated with increased implantation and pregnancy rates compared to fresh single euploid ET with PGS.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2006.10a
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• pp.47-48
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• 2006

• Clinical and Experimental Reproductive Medicine
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• v.49 no.4
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• pp.225-238
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• 2022

The ultimate goal of human assisted reproductive technology is to achieve a healthy pregnancy and birth, ideally from the selection and transfer of a single competent embryo. Recently, techniques for efficiently evaluating the state and quality of preimplantation embryos using time-lapse imaging systems have been applied. Artificial intelligence programs based on deep learning technology and big data analysis of time-lapse monitoring system during in vitro culture of preimplantation embryos have also been rapidly developed. In addition, several molecular markers of the secretome have been successfully analyzed in spent embryo culture media, which could easily be obtained during in vitro embryo culture. It is also possible to analyze small amounts of cell-free nucleic acids, mitochondrial nucleic acids, miRNA, and long non-coding RNA derived from embryos using real-time polymerase chain reaction (PCR) or digital PCR, as well as next-generation sequencing. Various efforts are being made to use non-invasive evaluation of embryo quality (NiEEQ) to select the embryo with the best developmental competence. However, each NiEEQ method has some limitations that should be evaluated case by case. Therefore, an integrated analysis strategy fusing several NiEEQ methods should be urgently developed and confirmed by proper clinical trials.