Developmental Ability of Somatic Cell Nuclear Transferred Embryos Aggregated at the 8-cell Stage or 16- to 32-cell Stage in Cattle
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Aggregation of somatic cell nuclear transfer (SCNT) embryos in mice is reported to improve full-term development. In the present study, we attempted to improve the development of SCNT embryos by aggregation in cattle. In Experiment 1, to examine the effect of the timing of aggregation on in vitro development of cumulus-cell NT embryos, we aggregated two or three SCNT embryos (2X or 3X embryos) at the 1-cell, 8-cell and 16- to 32-cell stages. Irrespective of the timing of aggregation, 3X embryos developed to the blastocyst stage at a high rate. However, aggregation did not improve the total blastocyst formation rate of the embryos used. The cell numbers of 3X embryos aggregated at the 1-cell stage and 2X embryos tended to be higher than that of single NT embryos (1X embryos). Furthermore, a significant increase in cell number was observed in 3X embryos aggregated at the 8-cell stage and 16- to 32-cell stage. In Experiment 2, we used fibroblast cells as nuclear donors and examined in vitro development of 3X embryos aggregated at the 8-cell stage and 16- to 32-cell stage. As a result, 3X embryos had high blastocyst formation rates and higher cell numbers than 1X embryos, which was consistent with the results of Experiment 1. In Experiment 3, we examined the full-term development ability of 3X embryos aggregated at the 8-cell stage and 16- to 32-cell stage. After transfer of fibroblast-derived NT embryos into recipient animals, a significantly higher pregnancy rate was obtained on Day 60 in 3X embryos than in 1X embryos. Two embryos aggregated at 8-cell stage and one embryo aggregated at the 16- to 32-cell stage developed to term, while no pregnancies derived from 1X embryos that lasted to Day 60. However, two of the cloned calves were stillborn. These results suggest that aggregation of the 8-cell stage or 16- to 32-cell stage SCNT embryos may improve the pregnancy rate, but that it cannot reduce the high incidence of fetal loss and stillbirth, which is often observed in bovine SCNT.
論文 | ランダム
- [警察政策研究]既刊目次一覧[創刊号(1997)〜第13号(2009)]
- 宮崎公立大学人文学部『紀要』通巻目次[創刊号(平成6年3月20日)〜第17巻第1号(平成22年3月5日)]
- 関西大学法学研究所『ノモス』刊行案内[創刊号 1990年〜第26号 2010年6月]
- 志学台考古 総目次(創刊号〜第10号)[2001年〜2010年]
- 脂質異常症・動脈硬化 脂質異常症 (社団法人日本透析医学会「血液透析患者における心血管合併症の評価と治療に関するガイドライン」)