• Clinical and Experimental Reproductive Medicine
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• v.33 no.4
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• pp.237-243
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• 2006

Objective: The aim of this study was to evaluate the efficacy of frozen-thawed ET in poor prognosis patients such as the old age (38~44 years; OA group) and the patients who did not achieve clinical pregnancy with the first fresh ET cycle (non-pregnant patients; NP group). Methods: Laboratory and clinical data were collected from fresh and frozen-thawed ET cycles of OA and NP group. Controlled ovarian hyperstimulation (COH) and conventional insemination or ICSI, in vitro culture and ET were performed by routine procedures. Supernumerary embryos were frozen by the slow freezing method, and frozen embryos were thawed by the rapid thawing method. Embryo development, pregnancy and implantation rates were statistically analyzed by Student t-test and chi square test Results: Mean ages were similar between fresh ET ($40.0{\pm}1.8$ years, n=206) and frozen-thawed ET ($39.9{\pm}1.9$ years, n=69) cycles in OA group. However, the clinical pregnancy and implantation rate of subsequent frozen-thawed ET significantly higher than those of fresh ET cycles (29.0% and 11.2% vs. 16.5% and 7.0%, p<0.05). In NP group, there was no difference in the mean age between fresh ET ($31.2{\pm}2.3$ years, n=40) and frozen-thawed ET ($31.9{\pm}3.1$ years, n=119) in subsequent cycles. The clinical pregnancy and implantation rates were similar between the subsequent fresh ET (42.5% and 22.6%) and the frozen-thawed ET (40.3% and 18.8%). Conclusion: In old age patients, higher pregnancy rate of frozen-thawed ET compared to fresh ET cycles in this study. It may be related that better uterine environments for implantation in frozen-thawed ET cycles than that of non-physiological hormonal condition in uterus of fresh COH cycles.

• Clinical and Experimental Reproductive Medicine
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• v.32 no.1
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• pp.65-70
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• 2005

본 연구는 이식 후 남은 잉여의 포배기 배아를 두 번의 냉동과 융해 과정을 반복적으로 실시한 후 이식한 결과에 관한 보고이다. 사람 포배기 배아의 동결보존에서 높은 생존율과 성공적인 임신율이 보고되고 있으나 미성숙 난자로부터 발달한 포배기 배아에 두 번의 초급속 냉동 방법을 실시한 후 이식한 보고는 되어 있지 않다. 이에 본 연구에서는 다낭성 난소 증후군 환자에게서 얻은 미성숙 난자로부터 발달한 포배기 배아를 artificial shrinkage 후 초급속 냉동함으로써 생존율을 높이는 방법을 이용하여 재냉동 이식하였을 때 임신에 성공한 증례를 보고하고자 한다. 29세의 환자로부터 채취한 55개의 미성숙 난자들(germinal vesicle stage oocytes)을 체외배양 하여 성숙한 37개의 난자들로부터 30개의 수정란을 얻을 수 있었다. 12개의 배아가 포배기 배아까지 발달하였으며 이 중 3개의 양질의 포배기 배아를 선별하여 이식하였고, 이식을 한 후에 남은 9개의 포배기 배아들은 artificial shrinkage의 과정을 마친 후에 초급속 냉동 방법을 이용하여 동결보존 하였다. 그 중, 4개의 포배기 배아들을 융해한 후 이식을 하지 않고 다시 재냉동을 하여 보관하였고 이 후 재냉동 되었던 4개의 포배기 배아들을 다시 융해 하여 이식을 한 결과 임신이 되어 건강한 남아를 분만하였다. 이로써 미성숙 난자로부터 얻은 포배기 배아가 두 번의 냉동과 융해의 과정을 통해 크게 손상을 입지 않고 생존할 수 있다는 것을 알 수 있었다. 그러므로 융해이식 후 남은 잉여의 포배기 배아를 다시 냉동 보관하여 다음 주기에 이용함으로써 축적된 임신율을 증가시킬 수 있을 것으로 사료된다.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.3
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• pp.197-205
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• 2007

Objective: This study evaluated the pregnancy and implantation rates in fresh IVF-ET cycles or frozen-thawed ET (F-ET) cycles based on serum estradiol concentrations of controlled ovarian hyperstimulation (COH). Methods: Clinical outcomes of 1,565 cycles of fresh IVF-ET with COH and 670 cycles of F-ET were retrospectively analyzed. Serum estradiol levels on the day of human chorionic gonadotropin (hCG) administration were categorized into Group-A (1,000$\sim$2,000 pg/ml), Group-B (2,000$\sim$3,000 pg/ml), Group-C (3,000$\sim$4,000 pg/ml) and Group-D (> 4,000 pg/ml). Clinical pregnancy (CPR), implantation (IR) and delivery rates (DR) were compared among four groups subdivided into younger (< 35 years) and older ($\geq$ 35 years) women. Statistical analysis was performed by Student's t-test and chi-square test. Results: Overall clinical outcomes with fresh IVF-ET and F-ET cycles were similar: 41.2% vs 44.8% of CPR, 18.8% vs 19.6% of JR, and 33.2% vs 34.5% of DR, respectively. There were no significant differences in the clinical outcomes of all four groups between fresh IVF-ET and F-ET cycles of younger women according to the estradiol levels. However, the clinical outcomes of F-ET cycles of older women in Group-D were significantly higher than those of fresh IVF-ET cycles (51.3% vs 25.0% of CPR*, 18.6% vs 9.9% of IR and 33.3% vs 19.4% of DR;* p<0.05). Conclusion: Our results demonstrated that supraphysiological levels of estradiol during COH in fresh IVF-ET cycles of older women ($\geq$ 35 years) may be detrimental to implantation environments of endometrium and clinical outcomes, which could be improved by F-ET cycles.

• 대한생식의학회:학술대회논문집
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• 2007.06a
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• pp.146-146
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• 2007

• Clinical and Experimental Reproductive Medicine
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• v.37 no.4
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• pp.307-319
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• 2010

Objective: Vitrification requires a high concentration of cyroprotectant (CPA) and an elevated cooling speed to avoid ice crystal formation. We have evaluated the effect of different combinations of cooling rate and CPA on embryonic integrity (developmental competence) in order to increase the efficiency of vitrification without impairing embryo viabilit. We hypothesized that the combination of CPA or the increase of cooling rates can reduce the concentration of toxic CPA for vitrification. As consequently, we performed experiments to evaluate the effect of various composition of CPA or slush nitrogen ($SN_2$) on the mouse embryonic development following vitrification using low CPA concentration. Methods: Vitrification of mouse embryos was performed with EM grid using liquid nitrogen ($LN_2$) or $SN_2$ and different composition of CPAs, ethylene glycol (EG) and dimethylsulfoxide (DMSO). After vitrification-warming process, their survival and blastocyst formation rates were examined. For analyzing long-term effect, these blastocysts were transferred into the uterus of foster mothers. Results: Survival and blastocyst formation rates of vitrified embryos were higher in EG+DMSO group than those in EG only. Furthermor, the group using $SN_2$ with a lower CPA concentration showed a higher survival of embryos and developmental rates than group using $LN_2$. Conclusion: The combination of EG and DMSO as CPAs may enhance the survival of mouse embryos and further embryonic development after vitrification. $SN_2$ can generate high survival and developmental rate of vitrified/warmed mouse embryos when a lower concentration of CPA was applied. Therefore, these systems may contribute in the improvement of cryopreservation for fertility preservation.

• 대한생식의학회:학술대회논문집
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• 2007.11a
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• pp.128-128
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• 2007

• Clinical and Experimental Reproductive Medicine
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• v.37 no.1
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• pp.57-64
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• 2010

Objectives: Likewise fresh cycle, it is also important to select right blastocysts for transfer in purpose of improving the pregnancy and implantation rates in frozen-thawed embryo transfer (ET) cycles. To investigate the relationship between the developmental velocity at the time of cryopreservation and pregnancy rates, we compared pregnancy rates between the day 5 cryopreservation group and the day 6 cryopreservation group. Methods: Transfers of frozen-thawed blastocysts which had been cryopreserved by vitrification on day 5 or day 6 were performed between January 2006 and June 2007. Ethylene glycol, DMSO, and pull and cut straws were used for vitrification and artificial shrinkage was done in expanded blastocysts. Thawing was performed on the day before transfer and thawed blastocysts were cultured in for 15~18 hrs in Quinn's blastocyct media. Blastocyst survival was assessed before transfer and post-thaw survival was defined as >50% of cells remaining intact and blastocoele re-expansion by the time of transfer. Results: Transfers of thawed blastocyst had been cryopreserved on day 5 were 52 cycles and 41 transfer cycles were cryopreserved on day 6. Patient characteristics, the number of transferred embryos and the survival rate of thawed blastocysts were not different in each cryopreservation day. But the biochemical pregnancy, clinical pregnancy, ongoing pregnancy, and implantation rate were significantly high in transfer of frozen-thawed blastocyst which were cryopreserved on day 5. Conclusions: The clinical pregnancy and implantation rate of day-5 blastocyst showed significantly higher than those of day-6 blastocyst in frozen-ET cycles. This result indicated that developmental rate of blastocyst at cryopreservation time in frozen-thawed cycle is discriminative marker of pregnancy outcome as like in fresh cycle.

• Journal of Veterinary Clinics
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• v.27 no.2
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• pp.154-158
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• 2010

Embryo Transfer (ET) is one of the assisted reproductive technologies and a useful tool for improving herds. The purpose of this study is to produce the calves using frozen embryos which were produced in the top one percent Holstein in Canada by ET. One hundred seventeen recipients were used for surrogate mothers and seventy cows were diagnosed to be pregnant. Fifty seven calves were born successfully and thirteen out of them failed to produce viable calves (abortion: 4, stillbirth: 9). Their gestational length, birth body weight and sex ratio for all the viable calves(n = 57) were $278.1{\pm}3.6$ days (range: from 271 to 286 days), $44.0{\pm}3.0\;kg$ (range: from 37 to 49 kg) and 57.9 vs. 42.1 % (male 33 and female 24), respectively. Microsatellite analysis confirmed that they were derived from frozen embryos. In conclusion, this study demonstrated that viable calves derived from frozen-thawed embryos from Canada were born by ET.

• 대한생식의학회:학술대회논문집
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• 1996.11a
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• pp.41-42
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• 1996

• Journal of Embryo Transfer
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• v.29 no.3
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• pp.235-240
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• 2014

Ethylene glycol (EG) has been successfully used as a cryoprotectant for vitrification of mammalian embryos (including human embryos) due to its low formula weight and high permeation into cells compared with other cryoprotectants, including propylene glycol (PROH). Cryopreservation is able to store the surplus pre-embryos for freezing and furthermore thawing and transfer in a subsequent cycle. This study was carried out to evaluate the effects of embryonic stage, cryoprotectant, and freezing-thawing method on the rates of survival and development of the cryopreserved mouse early embryo and finally to establish the cryopreservation method of surplus embryos obtained during assisted reproductive technology (ART). Female ICR mice (6~8 weeks old) were induced to superovulate by sequential intraperitoneal injection of 5 IU PMSG and 5 IU hCG 48 h apart. Mouse embryos were collected according to its developmental stage after the injection of hCG. Embryos were cryopreserved not only during cryoprotectant step (1~4 step) but also in a variety of media (HTF, IVF medium, D-PBS) and cell stage. The results were as follows : There is no clear advantage in these freezing media of rapid method, but 4 cell and 8 cell of slow method (2, 3 and 4 step) have advantage in D-PBS. The development of embryos according to cell stage become greater in 8 cell stage. In the treatment steps of cryopreservation, the development of embryo to blastocyst was similar among rapid method, but the development of 4 cell and 8 cell embryos to blastocyst according to slow method was better than rapid method.