![]() Although the microtransfer of donor nuclei from embryos has resulted in successful cloning in cattle and other species, there has been no nuclear cloning in the mammal using nuclei that have developed beyond the embryonic stage (Jones 1994). ![]() The donor nucleus then controls the development of the egg, which, once implanted and brought to term, results in a being genetically identical to the original. The second procedure, nuclear transplantation, involves taking the cell of an animal or human, removing the nucleus, and introducing it into an unfertilized egg from which the nucleus has been removed. Cohen 1994), but no reports of its use in normal human cells have been presented in the literature. This procedure has been used successfully to increase the pregnancy rate of cattle (J. The number of viable human embryos that can be produced by blastomere separation of a single embryo ranges up to four (J. Each separate cloned embryo, therefore, has the same genetic make-up as the original. #AMBERLIGHT PDF FULL#Cells at this stage are totipotent, which means that they have not begun to differentiate into specific tissues, such as bone or muscle, but carry their full genetic complement for development. Two quite different laboratory procedures aimed at duplicating embryos have been termed cloning: embryo splitting and nuclear transplantation.Įmbryo splitting, also known as blastomere separation, involves isolating individual cells or clusters of cells of very early embryos and growing them into separate embryos. In general, it refers to artificially induced asexual reproduction that produces beings genetically identical to the original from which they are cloned. While some commentators found no serious problems in proceeding with research of this sort, others speculated about the negative ethical and social implications of producing multiple copies of genetically identical humans.Ĭloning has several different meanings in the biological sciences. A major purpose of this research was to enhance the chances of pregnancy in infertile couples by increasing the number of embryos available for transfer into the womb. The embryos used were abnormal, however, and could not implant. From 17 very early embryos, 48 blastomeres-or theoretically 48 new totipotent embryos-were obtained. In 1993, investigators reported that they had successfully formed multiple embryos from single human embryos, as had been done previously in animals (Hall et al. ![]() The prospect of human cloning has reemerged as a frontier bioethical issue. ![]()
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