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Embryonic Stem Cells and Adult Stem Cells

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Embryonic stem cells are a different class of stem cells. ‘Stem cells’ are primitive cells with the capacity to divide and give rise to more identical stem cells or to specialize and form specific cells of somatic tissues. However, two types of stem cell can be distinguished: embryonic stem cells (ES): can only be derived from pre‐implantation embryos and have a proven ability to form cells of all adult tissues (termed ‘pluripotent’). ‘Adult’ stem cells, which are found in a variety of tissues in the fetus and after birth and are, under normal conditions, more specialized, which is revered to as “multipotent.” The embryonic stem cells can assist with tissue replacement and repair. (Wert, G., Mummery, C.) Adult stem cells are best known is the hematopoietic stem cell (HSC). They can be found in bone marrow and umbilical cord blood. These stem cells can be collected from new blood leaving the bone marrow by using a granulocyte colony-stimulating factor. Adult stem cells have generally been regarded as having the capacity to form only the cell types of the organ in which they are found; however, recently they have been shown to exhibit an unexpected versatility by reversing them into embryonic stem cells. Adult stem cells originating in one germ layer can form a variety of other derivatives of the same germ layer (e.g. bone marrow‐to‐muscle within the mesodermal lineage), as well as transdifferentiate to derivatives of other germ layers. There are different ways of collecting the different types of adult stem cells. The following are different types of adult stem cells: mesenchymal stem cells (MSC)- are also capable of differentiating into various types of cells (mainly mesodermal); myocytes (muscle cells); osteoblasts (bone ce... ... middle of paper ... ...2 weeks after fertilization. (Wert, G., Mummery, C.) However, the most potent stems cells are collected perinatal stem cells from aborted fetuses. These stem cells are totipotent, “Totipotent (cell are)… capable of developing into all the specialized cells that make up the adult animal.” (http://link.springer.com/chapter/10.1007%2F10_2008_45) Totipotent means unspecialized cells have the ability to change into any specialized cells. Researchers have discovered stem cells in amniotic fluid in addition to being in umbilical cord blood. They are taken from the amniotic fluid fills the sac that surrounds and protects a developing fetus in the uterus. Researchers have identified stem cells in samples of amniotic fluid drawn from pregnant women during a procedure called amniocentesis, which is a test for abnormalities. (Http://www.mayoclinic.com/health/stem-cells/CA00081)
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