Techniques of nuclear transfer and cell fusion have proven their value in embryonic studies of many non-mammalian animal species. Recently, these procedures have been successfully used in small laboratory mammals, particularly mice, to explore the potential of nuclei and cytoplasm from different sources to produce viable embryos when fused. However, applying the same approach to study embryonic developmental biology in large domestic animals faces many technical and practical difficulties, and thus far, no attempts have been reported to perform nuclear transfer in sheep embryos. In this article, I describe this procedure and its use to study the development of embryos that were fused from complete blastomeres of embryos containing 8 and 16 cells with halves of unfertilized hollow or defective oocytes. The procedure involves the division of a single-cell oocyte in a medium containing cytochalasin; fusing the oocyte halves with one blastomere, using Sendai virus or an electrical stimulation device; embedding them in agar, followed by culturing the reconstructed embryos in closed uterine horns of ewes during the quiet period. It has proven possible to obtain fully viable embryos using this procedure.
Abstract
Nuclear transfer and cell fusion techniques have demonstrated their value in embryonic studies of many non-mammalian animal species. Recently, these procedures have been successfully used in small laboratory mammals, particularly mice, to explore the potential of nuclei and cytoplasm from different sources to produce viable embryos when fused. However, using the same approach to study embryonic developmental biology in large domestic animals faces many technical and practical difficulties. To date, no attempts have been reported to perform nuclear transfer in sheep embryos.
Procedure and Results
In this study, the nuclear transfer procedure in sheep embryos was described and utilized to study embryo development. Complete blastomeres from embryos containing 8 and 16 cells were fused with halves of unfertilized hollow or defective oocytes. The procedure involved the division of a single-cell oocyte in a medium containing cytochalasin, followed by fusing the oocyte halves with one blastomere using Sendai virus or an electrical stimulation device. Subsequently, the reconstructed embryos were embedded in agar and weighed in closed uterine horns of ewes during the quiet period. The results showed that fully viable embryos can be obtained using this procedure.
Conclusion
This study concluded that nuclear transfer in sheep embryos is possible and leads to the production of fully viable embryos. This finding is significant in the field of embryonic developmental biology and may contribute to a better understanding of the embryonic developmental process in large animals. However, there remain technical and practical challenges that need to be overcome before researchers can widely use this procedure in embryonic studies of large domestic animals.
Source: https://www.nature.com/articles/320063a0
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