What are stem cells?
Stem cells are the master cells of the human body. They can divide to produce copies of themselves and many other types of cell. They are found in various parts of the human body at every stage of development from embryo to adult. Stem cells taken from embryos that are just a few days old, can turn into any of the 300 different types of cell that make up the adult body.
Why are stem cells useful?
Because stem cells are so versatile, they could potentially be used to repair and replace damaged human tissue. In future, it is hoped that stem cells could be used to treat and cure a variety of diseases and injuries including Parkinson's disease, stroke and diabetes.
Where do the embryos come from?
Embryonic stem cells can be taken from spare human embryos left over from fertility treatments, or from cloned human embryos developed in the laboratory. This can only occur if fully informed consent has been obtained from the donors. One method for making cloned embryos is called nuclear transfer. During this process, genetic material or DNA from a donor is inserted into an empty egg cell. After the resulting hybrid cell has been 'activated' (normally using an electrical pulse), it begins to divide, creating new cells and forming a cloned embryo.
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