• Clinical and Experimental Reproductive Medicine
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• v.30 no.1
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• pp.57-64
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• 2003

Objective : We investigate the effects of multiple attempts of embryo transfer because of retained embryos in the catheter and of contaminated mucus on the transferred catheter. Materials and Methods: We respectively analysed data between November 1998 and August 2002 from 305 patients of 369 cycles who underwent IVF-ET. Of these patients, 47 patients of 50 cycles (Group 2) were required multiple trial of embryo transfer. They were compared with an age-matched control groups (Group 1) with female factor infertility. Pearson's $?^2$ and Fisher's tests were used to compare proportions between discrete variables. Noncategorical data were compared using t-test. Statistical significance was set at p<0.05. Results: Embryos were significantly more likely to be retained when catheter was contaminated with mucus (Group 1: 22.4%; Group 2: 44.0%). The clinical pregnancy rates, however, for the contaminated mucus or not, were 46.8%, 43.5% respectively. There was no significant difference clinical pregnancy rate between those who had all their embryos transferred at the first attempt (45.4%) and those who required more than one attempt (48.0%). Conclusions: Contaminated mucus in the catheter is associated with failed embryo transferred at the first attempt. Embryo transfers, however, that are repeated attempts do not adversely affect pregnancy rates following IVF-ET.

• Clinical and Experimental Reproductive Medicine
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• v.43 no.2
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• pp.133-138
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• 2016

Objective: To determine the incidence of embryo retention (ER) in the transfer catheter following embryo transfer (ET) in blastocyst transfer and investigate whether retransferring retained embryos has an impact on reproductive outcomes in patients undergoing in vitro fertilization-ET. Methods: We retrospectively analyzed the records of 1,131 blastocyst transfers, which comprised 223 single blastocyst transfer (SBT) and 908 double blastocyst transfer (DBT) cycles. Each SBT and DBT group was classified depending on whether ET was performed without retained embryos in the catheter during the first attempt (without-ER group) or whether any retained embryos were found following ET (ER group) for the purpose of comparing reproductive outcomes in a homogenous population. Results: The overall incidence of finding retained embryos was 2.8% (32/1,131). There were no retained embryos in SBT cycles. In DBT cycles, implantation rates (30.0% vs. 26.6%), positive ${\beta}-hCG$ rates (57.2% vs. 56.2%), clinical pregnancy rates (45.3% vs. 46.9%), and live birth rates (38.9% vs. 43.8%) were not significantly different between the without-ER and ER groups. There were no significant differences in the mean birth weight (g) $2,928.4{\pm}631.8$ vs. $2,948.7{\pm}497.8$ and the mean gestational age at birth ($269.3{\pm}17.2days$ vs. $264.2{\pm}25.7days$). A total of nine cases of congenital birth defects were found in this study population. Eight were observed in the without-ER group and one in the ER group. Conclusion: Our results suggest that retransfer of retained embryos does not have any adverse impact on reproductive outcomes in blastocyst transfer cycles. Furthermore, our results support finding that SBT might be advantageous for decreasing the incidence of retained embryos in catheters.

• 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.

• Journal of Embryo Transfer
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• v.9 no.1
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• pp.31-41
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• 1994

핵 이식 기술을 이용한 cloning 송아지 생산이 처음 보고(Prather et al., 1987) 된 후, 소 수정란 Cloning에 대한 많은 연구가 분자 생물학 등 여러 분야에서 꾸준히 계속되고 있다. 이 기술은 빈우의 번식 능력을 향상시켜 유전적 개량량을 증대할 수 있는 번식과 육종을 위한 도구로써 많은 잠재력을 지니고 있다. 최근 핵 이식 기술을 이용하여 유전적으로 우수한 빈우로부터 수천개의 수정란을 생산하여, 이들 수정란에게 생산된 송아지가 번식 축군으로 공시되어 있으므로, 그 결과가 주목되나 아직까지는 비용이 많이 들고 송아지 생산 효율이 저조하므로, 가까운 장래에 일반 양축가에 이용될 가능성이 낮다. 그러나 이 기술의 실용화를 위하여 선결되어야 할 많은 문제점들 중, 지난 몇 년 동안 많은 연구기관에서 수행된 활발한 연구의 결실로써, 난포란 제핵, cell fusion 과 oocyte activation의 방법등 주요 장애 요인들이 점차 극복되면서 실용화를 위한 접근이 예견되어지며, 구미의 일부 개량 기관에서는 이를 상업화 하기 위한 여건을 다지고 있다. 그러므로 이 Review에서는 fllicular dynamics, 난포란의 성숙, cell cycle, 난포란 제핵, cell fusion과 oocyte activation, 이식후 핵의 remodeling과 reprogramming에 대한 현재까지의 보고된 자료를 기초로 그 기본 원리를 재고하는데 초점을 맞추었다.

• Journal of Embryo Transfer
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• v.32 no.4
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• pp.319-324
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• 2017

This study is to compare the effect of estrus synchronization and embryo transfer between Korean and Mongolian cattle. Embryos were collected from 9 donors housed in Asan city in South Chungcheong Province, South Korea. Embryos were collected 9 donors from Khushaat sum, Selenge province and Bayanchandmani sum, Tov province in Mongolia. Follicle Stimulating Hormone (FSH), Controlled Internal Drug Release (CIDR) and Prostaglandin (PG) were used for superovulation. Subsequently, Artificial Insemination (AI) was done for donor cow and embryo was collected after 7 and 8 days. Collected embryos were compared between Mongolian and Korean cattle. Finally, good quality and fresh embryos were transferred to 50 and 22 recipients of cows in Korea and Mongolia respectively. The findings show that Korean native cattle each donor cow produced on an average 16.9 embryos and, 10.9 embryos were found transferable. But in case of Mongolia the average production of embryos per donor cow was 8.6 embryos and, 6.2 embryos were found transferable. Embryo collection after 7 and 8 days was not difference in embryo production in Korea. But, in Mongolia embryo production after 8 days was found more efficient than the 7 days. Korean native recipient's cows (74.6%) and Mongolian recipient's cows (71.0%) respectively were found transferable ovarian stage. The result suggested that efficiency of embryo production from the superovulation method treated of Korean cow were higher than the Mongolian cow. The pregnancy rate of Korea native cattle was 72%, which was about 10% higher than that of Mongolia cattle.

• Clinical and Experimental Reproductive Medicine
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• v.27 no.1
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• pp.75-81
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• 2000

Objective: The objective of this study is to influence of sequential embryo transfers in an invitro fertilization was examined. Method: After in vitro fertilization, a maximum of 6 fertilized oocytes was enrolled in this study. At day 3 after an oocytes retrieval, embryos with good quality were transferred (mean 4.9), remaining embryos (mean 2.0/cycle) were cryopreserved at blastocyst stage (Group 1). At day 5 after oocytes collection, second a embryo transfer (mean 1.2/cycle) was performed, if one of these embryos had reached the blastocyst stage (Group 2) using P1 supplemented with 10 SSS and 30% Follicular fluid. No statistical difference in the pregnancy rate could be seen between the group without a second embryo transfer (n=21; 28.6%) and the group with a second transfer (n=52; 28.8%). Results: The incidence of multiple pregnancy rate per embryo transfer was not statistically different between both group and no high-rank multiple pregnancy (greater than triplete) were observed (0.9%, 15.4%, respectively, p=0.74, ${\chi}^2$). Out of 114 cycles (506 embryos) cultured embryos in group 2, 52 cycles (159 embryos, 29.8%) reached the blastocyst stage. Conclusion: The second transfer did not have a significant effect on the pregnancy rate. The most important factor for the pregnancy seems to be the quality of the embryos transferred on day 3 following oocyte retrieval. We recommend embryo transfer is performed only one, day $2{\sim}3$ or D5.

• Clinical and Experimental Reproductive Medicine
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• v.50 no.4
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• pp.277-284
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• 2023

Objective: In this retrospective study, we analyzed factors influencing the ongoing pregnancy rate (PR) in women with repeated implantation failure (RIF) undergoing embryo transfer with endometrial receptivity array (ERA). Methods: Eighty-three consecutive personalized embryo transfers (pETs) with ERA, from 54 women with RIF, were selected from June 2020 to April 2022. Vitrified blastocyst transfer was timed based on ERA results. Results: The ongoing PR per pET was 33.7%. Using ERA, the endometrium was identified as pre-receptive in 26 cycles, early receptive in 25 cycles, receptive in 31 cycles, and late receptive in one cycle. With cycles categorized into three receptivity phases (pre-receptive, early receptive, or receptive), no significant differences were found in the clinical PR (27.3%, 55.6%, and 40%, respectively) or ongoing PR (9.1%, 55.6%, and 40%, respectively) after a single blastocyst transfer. Similarly, no significant differences were observed in the clinical PR or ongoing PR after the transfer of two or more blastocysts. Among women with ongoing pregnancy relative to those without, age at first pET was significantly lower (35 years vs. 39 years, p=0.001), while blastocyst score (23 vs. 18, p=0.012) and the proportion of blastocyst scores >18 (71.4% vs. 38.9%, p=0.005) were significantly higher. In multiple logistic regression analysis, the woman's age (odds ratio [OR], 0.814; 95% confidence interval [CI], 0.706 to 0.940; p=0.005) and blastocyst score >18 (OR, 3.052; 95% CI, 1.075 to 8.665; p=0.036) were identified as significant factors influencing ongoing pregnancy. Conclusion: In pET with ERA, ongoing pregnancy was closely associated with woman's age and blastocyst quality.

• Reproductive and Developmental Biology
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• v.33 no.4
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• pp.257-262
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• 2009

This study was to investigate pregnancy rate of IVM/IVF/IVC Korean cattle (registered in government) embryos according to transport time course. For the production of embryos, oocytes recovered from slaughtered excellent grade cow and highly motile frozen-thawed bull semen (purchased from LIMC, KPN#497) was used. In vitro produced embryos were cultured in CR1aa medium for 8 days and some of them were frozen. The rate of average cleavage (>2-cell) was 83.0% (308/371) and blastocyst rate at day 8 was 34.7% (107/308). Among in vitro produced blastocyst embryos at day 8, most healthy embryos were freshly transferred on production day and some frozen embryos were direct transferred on appropriate day. These embryos were produced in a laboratory, embryo transfer (ET) was planned in 10 areas of the remote island (Jeju) from the laboratory by airplane. Thus, we examined the pregnancy rate in recipient cow according to embryo of transport time course before ET. From embryo transferred 44 recipient cows, overall pregnancy was 40.9% (18/44), these 18 cows were all calved [single, 94% (17/18); twin, 6% (1/18)] and total embryo implantation rate was 26% (19/66). Comparing transport time in the base of 6 hr, pregnancy rate in ET group required less 4 hr (60%, 9/15) was significantly higher than that required more 6 hr (26.3%, 5/19). In direct ET of freezing embryos, the pregnancy rate was 40% (4/10). However, it was difficult to find the meaning of temperature, pH and corpus luteum quality of recipients on comparison of pregnancy rate. When the cell death level of embryos according to storage time in thermos (straw container) before ET was measured by TUNEL staining, apoptotic index was increased with storage time-dependent. These results demonstrated that long distance transfer of IVM/IVF/IVC embryos is possible and the time of embryo transport is very important for the pregnancy rate on field trial.

• Clinical and Experimental Reproductive Medicine
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• v.16 no.2
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• pp.187-204
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• 1989

This is a report concerning IVF-ET program and its outcomes of the reproductive center of the Ohio State University(OSU). The pregnancy rate/laparascopy in the OSU reproductive center was average 12.2%. However, the fertilization rate was lower than other reporters. The other problem of the OSU reproductive center was that there was no success in the field of cryopreserved embryo and donor embryo. Therefore, many aspects such as hyperstimulation protocol, culture systems, and embryo transfer technique should have to be reevaluated in order to enhance the outcome of IVF-ET program in the OSU reproductive center.

• Clinical and Experimental Reproductive Medicine
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• v.12 no.1
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• pp.15-29
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• 1985

최근 몇년전부터 한국에서도 In Vitro Fertilization - Embryo Transfer Program(IVF-ET)에 대한 논의가 있어왔다. 현재 몇몇 종합병원 및 개인 산부인과 의원에서 수십명의 난관 유착환자를 위한 IVF가 시도되었으나 아직까지, 한건도 성공되었다는 보고는 없다. 몇 십명이 실험적 모델로 제공되었으나 한 건의 성공사례도 없었다는 것은 문제점이 있는 것이 분명하며 이러한 한국에서의 문제점을 시설 문제와 전문가 또 IVF 과정에서의 technical problem들을 종합해서 다루어 보고져 하는 것이 본 논의의 주제임을 먼저 밝혀둔다.