• Clinical and Experimental Reproductive Medicine
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• 제49권3호
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• pp.159-167
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• 2022

As the resolution and accuracy of diagnostic techniques for preimplantation genetic testing for aneuploidy (PGT-A) are improving, more mosaic embryos are being identified. Several studies have provided evidence that mosaic embryos have reproductive potential for implantation and healthy live birth. Notably, mosaic embryos with less than 50% aneuploidy have yielded a live birth rate similar to euploid embryos. This concept has led to a major shift in current PGT-A practice, but further evidence and theoretically relevant data are required. Proper guidelines for selecting mosaic embryos suitable for transfer will reduce the number of discarded embryos and increase the chances of successful embryo transfer. We present an updated review of clinical outcomes and practice recommendations for the transfer of mosaic embryos using PGT-A.

• 한국수정란이식학회지
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• 제30권3호
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• pp.229-237
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• 2015

To improve the developmental potential of bovine somatic cell nuclear transfer (SCNT) embryos, this study compared the developmental rates to blastocyst stage in the SCNT embryos using donor fibroblasts treated with 5-azacytidine (5AC) and S-adenosylhomocysteine (SAH) at different concentrations. Their reprogramming efficiency level was investigated with level of telomerase activity. Donor fibroblasts isolated from adult ear skin of a cow were exposed to 5AC and SAH at different concentrations during 2 passages. After nuclear transfer into enucleated recipient oocytes, the cleavage and developmental rates were significantly (p<0.05) decreased in the SCNT embryos using 5AC-treated fibroblasts (5AC-SCNT embryos), compared with those of non-treated control (control-SCNT embryos) and SAH-treated fibroblasts (SAH-SCNT embryos). The developmental rates to blastocyst stage tended to be slightly increased in the SAH-SCNT embryos at each of the concentrations, and especially, the developmental rates in the SCNT embryos using 1.0 mM SAH-treated fibroblasts were significantly (p<0.05) higher than that of control SCNT embryos. The mean numbers of total and ICM cell in blastocysts were also significantly (p<0.05) decreased in the 5AC-SCNT embryos, compared with those of other SCNT blastocysts. Further, the level of telomerase activity was also significantly (p<0.05) decreased in the 5AC-SCNT embryos than those of control and SAH-SCNT embryos. Whereas, a significantly (p<0.05) up-regulated telomerase activity was observed in SAH-SCNT embryos, compare with that of control-SCNT embryos. In conclusion, SCNT embryos using hypomethylated donor cells with SAH, not 5AC, may improve the developmental potential and reprogramming efficiency.

• 한국수정란이식학회지
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• 제9권1호
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• pp.43-48
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• 1994

This study was carried out to produce monozygotic twin calves by transfer of bisected embryos. Four Korean native cattle donors were superovulated with FSH and flushed to collect embryos on day 6 or 7 of the estrus cycle. Morula and early blastocyst embryos showed 1 or 2 grade were bisected with microblade and each set of demi-embryos without zona pellucida were transferred nonsurgically to 10 recipients respectively. The results obtained were as follows; 1. Twenty four demi-embryos (92.3%) were separated from 13 original embryos and among them 20 demi-embryos (83.3%) had normal appearance without severe damage. 2. Four sets of fresh demi-embryos were transferred to 4 recipients and one recipient was twin pregnant 3. Six sets of frozen-thawed demi-embryos were transferred to 6 recipients. Two recipients were pregnant, one of them twin.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2001년도 춘계학술발표대회
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• pp.11-11
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• 2001

In this study, we examined the developmental potential of reconstructed bovine embryos and the fate of donor mitochondria during their preimplantation development after nuclear transfer. Isolated cumulus cells were used as donor cells in nuclear transfer. Cumulus cells labelled with MitoTracker Green FM fluorochrome were injected into enucleated bovine MII oocytes and cultured in vitro. MitoTracker labelling on donor cells did not have a detrimental effect on blastocyst formation following nuclear transfer. Cleavage rate was about 69%(56/81) and blastocyst formation rate was 6.2% (5/81) at 7 days after nuclear transfer. The labelled mitochondria dispersed to the cytoplasm and became distributed among blastomeres and could be identified up to the 8- to 15-cell stages. Small patches of mitochondria were detected in some 8- to 15-cell stage embryos (5/20). However, donor mitochondria were not detected in embryos at the 16-cell stage and subsequent developmental stages. In the control group, mitochondria could be identified in arrested 1-cell embryos up to 7 days after nuclear transfer These results suggest that donor mitochondria disappear from recipient cytoplasm before 16-cell stage following nuclear transfer in reconstructed bovine embryos.

• 한국수정란이식학회지
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• 제15권3호
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• pp.219-230
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• 2000

This study was carried out to determine the factors on achieving good viability of embryos biopsied fur sexing, to investigate pregnancy rate following embryo transfer(ET) with sexed embryos, and to confirm the accuracy for the calves bort following ET with sexed embryos by polymerase chain reaction(PCR). To investigate viability of Hanwoo embryos after biopsy for sexing, fresh and frozen/thawed embryos were biopsied according to different developmental day of blastocysts, different stage of blastocysts, and different biopsy grade and the embryos themselves were incubated for 2 hours in TCM199 after microsection to be evaluated morphologically for recovery as blastocyst. The results obtained were as follows : 1. The rate of oocytes cleaved in vitro and the rate of blastocyst of the cleaved oocytes were 52.5% and 21.6%, respectively. The rate of blastocyst on day 8 was 11.2%, denoting the highest rate during whole culture period posterior to in vitro fertilization(IVF) 2. After biopsy for sexing, the viability rate of blastocyst on day 7, 8 and 9 was 75.0%, 88.4%, and 100.0%, respectively and the viability of early, mid, and expanded blastocyst after biopsy was 75.0%, 88.9%, and 91.1%, respectively The viability rate of fresh and frozen/thawed embryos was 89.9%, 71.4%, respectively. And the viability of expanded, hatching, and hatched blastocyst of frozen/thawed embryos was : 75.0%, 75.0%, and 50.0%, respectively. The viability of embryos according to biopsy grade of 10∼20%, 21∼30%, and 31∼40% was 85.7%, 91.5%, and 71.4%, respectively. 3. Pregnancy rate after transfer with biopsied embryo between flesh and frozen/thawed embryos was 22.6% and 20.0%, respectively. 4. In comparison between sex by PCR method and sex of calves born after embryo transfer, the accuracy of sex deterimination was 92.3% (12/13).

• 한국수정란이식학회지
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• 제11권2호
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• pp.95-101
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• 1996

The present study investigated the effect of treatment with nocodazole on the efficiency of cell cycle synchronization and development of mouse 4-cefl embryos. In addition, developmental ability of reconstituted embryos that received nuclei from 4-cell embryos synchronized with nocodazole at M phase was examined in vitro and in vivo. (1) When 4-cell blastorneres exposed to culture medium containing l$\mu$g /ml nocodazole for 2, 4, 6 and 8 hrs, 40% (40/10l), 75% (l19/159), 85% (87/102) and 97% (155/160) of nuclei were synchronized at M phase, respectively. (2) Treated with nocodazole for 4 hrs, the proportion of 4-cell embryos developed to blastocysts (98%, 60/61) was not significanUy different from that of the control embryos (98%, 196/201). However, the developmental ability of 4-cell embryos treated for 8 (87%, P<0.05)and 12 hrs (76%, P

• 한국수정란이식학회지
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• 제8권2호
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• pp.105-109
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• 1993

This study was carried out to propagate Korean native cattle using beef recipients by embryo transfer. Seven Korean native cattle donors were superovulated with FSH 32mg and Embryos collected from donors were frozen and preserved in National Animal Breeding Institute. Frozen-thawed embryos were transferred to synchronized 40 beef recipients nonsurgically in Daekwanryeong Branch of National Animal Breeding Institute. The results obtained were as follows : 1. Total ova and transferable embryos per donor were 11.4 and 11.1 from 7 donors, respectively. 2. Among 40 recipients transferred with frozen-thawed embryos, 20 were pregnant(50.0%). 3. The pregnancy rate according to time from embryo thawing to transfer was higher when transferred within 3 hours than after 3 hours(57.6% vs. 14.3%). 4. The cow recipients showed slightly higher pregnancy rate than the heifer(53.3% vs. 48.0%). 5. Two grade embryos showed higher pregnancy rate than 1 grade(66.7% vs. 45.2%).

• 한국수정란이식학회:학술대회논문집
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• 한국수정란이식학회 2002년도 국제심포지엄
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• pp.3-7
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• 2002

In vitro embryo culture techniques provide significant contributions not only for a basic research of fertilization and early embryogenesis, but also for a low cost mass production of bovine embryos for transfer, embryo diagnosis, nuclear cloning and the production of transgenic cows. This presentation introduces newly developed serum-free media (IVD101 and IVMD101) that are effective far high yields of transferable embryos of excellent quality from in vitro-matured and fertilized oocytes. Both serum-free media are superior to a conventional serum-containing medium on the increased rates of blastocyst formation, post-thaw embryo viability, and pregnancy after transfer. Furthermore, reduced risks of calf mortality and large calf syndrome are also observed for the serum-free-derived embryos. Serum-derived embryos contain a large number of lipid droplets and immature mitochondria in their cytoplasm that may account for the lower production of transferable embryos and poor embryo quality.

• 한국수정란이식학회지
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• 제3권1호
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• pp.6-12
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• 1988

The possibility of embryo transfer technique in pigs to introduce a new genetic material into closed herds for disease control was investigated. The results investigated were as follows: 1. The exhibiting rate of estrus on the administration of altrenogest and PMSG ranged from 83.3 to 100% and the estrus exhibited within 4.0 - 5.3 days after the administration of altrenogest. 2. The average number of ovulation points per pig by the injection of PMSG and HCG were 14.0 - 30.7. 3. The average number of recovered embryos per pig was 15.7, and 72.8% of embryos were recovered. 4. The pregnancy rate of recipients was 63.6% and the survival rate of transferred embryos were 21%. 5. When the 1-cell embryos were cultured for 24hrs, they were all developed. Therefore it is possible to recover and preserve the embryos from the donor pigs which have high genetic ability, and to transfer embryos to recipient pigs which are separated from donor pigs in Korea.

• Asian-Australasian Journal of Animal Sciences
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• 제12권8호
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• pp.1188-1191
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• 1999

Primordial germ cells (PGCs) of White Leghorn chicken embryos as a donor were transferred to Rhode Island Red chicken embryos as a recipient. At 48-50 h (stage 13-15) of incubation of fertilized eggs, donor PGCs, which were taken out from blood vessels of donor embryos, were injected into blood vessels of recipient embryos. Sex of the treated embryos was determined after the transfer of PGCs using remaining blood samples. In the present experiments, survival rate of the treated embryos was 33.3% for homo-sexual and 35.4% for hetero-sexual transfers of PGCs, respectively, when determined at 17 days of incubation. In this study, most of the treated embryos could not survive more than 18 days of incubation, though the reason for that was not clarified in the present work. The gonalds removed from embryos that died after 18 days of incubation and the organs from newly hatched chicks were examined for morphological and histological features. The gonads removed from the embryos with homo-sexual transfer of PGCs showed normal development in appearance. On the contrary, some (35.3%) of the embryos with hetero-sexual transfer of PGCs possessed abnormal gonads similar to ovotestis by histological observation. In cases where the gonads developed to be normal organs (64.7%) the sex of embryos was the same as recipient ones. The present results suggest that hetero-sexual transfer of the PGCs may bring about the possibility of development of the embryos bearing sexually different gametes, spermatogonia or oogonia.