![]() ![]() Excess blastocysts are sometimes donated for research purposes after obtaining Used for reproductive purposes, IVF usually produces an abundance of viable blastocysts. The largest source of blastocysts for stem cell research comes from Despite coming from different sources, according to NIH, the resultant cells seem to be the same. Gearhart and his team noted the same observations as Thomson’s team. The paper detailed the process by which pluripotent stem cells were derived from gonadal ridges and mesenteries extracted from aborted five-to-nine week old human embryos. “Derivation of Pluripotent Stem Cells from Cultured Human Primordial Germ Cells” in Proceedings of the National Academy of Science. Johns Hopkins School of Medicine, published “Embryonic Stem Cell Lines Derived from Human Blastocysts,” in the 6 November Science issue. Since the three germ layers precede differentiation into all the cell types in the body, this observation suggested that the cultured cells were pluripotent. Thomson’s team also observed derivatives of all the three germ layers–endoderm, mesoderm, and ectoderm. They were capable of long-term self-renewal and thus could remain undifferentiated for long periods of time they had particular surface markers and they were able to maintain a normal and stable karyotype. The characteristics of the cultured cells were consistent with previously identified features in animal stem cells. Thomson and his team of researchers cultured human embryonic stem cells from the inner cell mass of donated embryos originally produced for in vitro fertilization. Wisconsin National Primate Research Center, located at the University of Wisconsin-Madison, In November 1998, two independent publications announced the first successful isolation and culture of pluripotent human stem cells. As of 2009, embryonic stem cells refer to pluripotent cells that are generally derived from the inner cell mass of blastocysts. At this point the cells in the inner cell mass have not yet differentiated, but have the ability to develop into any specialized cell type that makes up the body. When the sphere and inner cell mass are fully formed, around day 5, the pre-implantation embryo is referred to as aīlastocyst. A mass of about thirty cells, called the inner cell mass, forms at one end of the sphere and eventually becomes the body. By day four, cells begin to separate and form a spherical layer which eventually becomes the placenta and tissue that support the development of the future fetus. At the eight-cell stage, roughly the third day of division, all eight cells are considered totipotent, which means the cell has the capability of becoming a fully developed human being. Between fertilization and the eighth week of gestation, the embryo undergoes multiple cell divisions. According to US National Institutes of Health (NIH), in humans, the term “embryo” applies to a fertilized egg from the beginning of division up to the end of the eighth week of gestation, when the embryo becomes a fetus. Embryonic stem cells are a particular type of stem cell derived fromĮmbryos. Stem cells are undifferentiated cells that are capable of dividing for long periods of time and can give rise to specialized cells under particular conditions.
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