• Title/Summary/Keyword: Cloned Embryo

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Current Status and Prospects of Nuclear Transplantation Technology for Production of Cloned Animals (복제동물 생산을 위한 핵이식기술의 개발 현황과 전망)

  • 이효종
    • Journal of Veterinary Clinics
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    • v.16 no.1
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    • pp.163-176
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    • 1999

  • The nuclear transplantation technique is known as the most potential and efficient method for producing large numbers of genetically identical animals from a single embryo and somatic cells. After Dolly was introduced in 1997, many scientists were amazed. A possibility came to a reality that live offspring could be produced with differentiated somatic cells from an adult animal. On the other side, many in the press and the sensationalists focused on the socially, ethically and scientifically unacceptable sides of the technology. In this article, the history, current status and prospects of the technological development of nuclear transplantation in mammals and its application to the production of cloned animals are described. For the efficient and successful production of cloned embryos by nuclear transplantation, the right selection, preactivation and micromanipulation of oocytes as capacious recipient cytoplasm, the adequate and benefitial preparation of multiple totipotent embryonic and somatic cells as donor nuclei, fusion of them and in vitro production of cloned embryos are very critical. Recently the overall efficiency of production of cloned embryos and offspring in livestock has been much improved. Cloning will also be a more efficient, faster and useful way of creating transgenic fetuses for gene therapies, gene pharming, organs for xenotransplantation by preselection and mass production of transgenic embryos and consequently improving the production efficiency in transgenic animals. Further technical development of nuclear transplantation will enable large-scale production of cloned livestock and in near future the commercial cloning of animals will become a reality.

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Production of cloned Rabbits Embryos and Offsprings by Nuclear Transplantation using In Vitro Matured Oocytes in Rabbits (토끼의 체외배양 난자를 이용한 핵이식으로 복제수정란 및 복제산자의 생산)

  • 박충생;전병균;이경미;윤희준;이효종;곽대오;최상용
    • Journal of Embryo Transfer
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    • v.10 no.1
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    • pp.65-72
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    • 1995

  • The purposes of this study were to produce cloned rabbit embryos and offsprings by nuclear transplantation(NT) using in vitro matured oocytes as nuclear recipient cytoplasm and to determine the effect of frozen nuclei donor embryos on the production efficiency of cloned embryos. The 8cell embryos were collected from the mated does by flushing oviducts with Dulbecco's phosphate buffered saline containing 10% fetal calf serum(FCS) at 40 hours after hGG injection. A portion of collected embryos were preserved at 4$^{\circ}C$ for 24 hours and a portion of them were frozen by vitrification method. The embryos used for donor nuclei were synchronized in the phase of Gi /S transition. The in vitro matured oocytes were used as recipient cytoplasm following removing the nucleus and the first polar body. The synchronized blastomeres from fresh, cooled or frozen embryos were injected into the enucleated oocytes by micromanipulation and were electrofused by electrical stimulation of three pulses for 60 $\mu$sec at 1.0 W /cm in 0.28 M mannitol solution. The fused oocytes were co-cultured with a monolayer of rabbit oviductal epithelial cells in M-199 solution containing 10% FCS for 120 hours at 39$^{\circ}C$ in a 5% $CO_2$incubator. Following in vitro culture of the NT embryos to blastocyst stage, they were stained with Hoechst 33342 dye for counting the number of blastomeres by fluorescence microscopy. The nuclear transplant embryos developed in vitro to 2- to 4-cell stage were transferred into the oviducts of synchronized recipient does. The results obtained were summarized as follows: 1. The fusion rates of the blastomeres from fresh, cooled and frozen embryos with the in vitro matured and enucleated oocytes were 100, 95.8 and 64, 3%, respectively. 2. Development in vitro to blastocyst was significantly(p<0.05) different between the cloned embryos with the blastomeres from fresh, cooled or frozen embryos as 39.0, 20. 9 and 15.7%, respectively. 3. The mean numbers of cell cycle per day during in vitro culture of cloned embryos blastomeres from fresh, cooled or frozen embryos was 1.31, 1.29 and 1.16, respectively. 4. A total of 77 nuclear transplant embryos were transferred into 6 recipient does, of which two offsprings were produced from a foster mother 31 days after embryo transfer.

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