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'''Adult stem cells''' are pluripotent, semi-differentiated, [[cell]]s that exist in all tissues.  "Adult stem cell", however, is not the preferred term used in the field to refer to them&#8212;developmental biologists will usually refer to them as a specific cell type (usually referencing genes they express) or as a tissue-specific stem cell.  They function to maintain tissue homeostasis by dividing to replace damaged or senescent somatic cells.  The two most well-studied examples of adult stem cells are the hematopoietic stem cells, which give rise to blood cells, and the intestinal crypt stem cells, which give rise to the intestinal epithelium.<ref>http://9e.devbio.com/</ref>

'''Adult stem cells''' are multipotent, semi-differentiated, [[cell]]s that exist in all tissues.  "Adult stem cell", however, is not the preferred term used in the field to refer to them&#8212;developmental biologists will usually refer to them as a specific cell type (usually referencing genes they express) or as a tissue-specific stem cell.  They function to maintain tissue homeostasis by dividing to replace damaged or senescent somatic cells.  The two most well-studied examples of adult stem cells are the hematopoietic stem cells, which give rise to blood cells, and the intestinal crypt stem cells, which give rise to the intestinal epithelium.<ref>http://9e.devbio.com/</ref>

As pluripotent cells, most adult stem cell types can generate cells of several different types.  However, because they are already epigenetically programmed to favor a particular fate, they generally cannot generate cell types outside of their lineage without genetic manipulation.

As multipotent cells, most adult stem cell types can generate cells of several different types.  However, because they are already epigenetically programmed to favor a particular fate, they generally cannot generate cell types outside of their lineage without genetic manipulation.

Identifying and characterizing stem cells within all adult tissues is an area of much intense ongoing research.  Understanding the mechanisms underlying the regulation of these stem cells has led to many recent breakthroughs in the field of cancer biology.  A recent paradigm-shift in cancer biology was the discovery that cancer is a disease resulting from dysregulation of adult stem cells.  The clinical implications of this concept are still being explored.  Obviously, there is still much in this field that remains unknown.

Identifying and characterizing stem cells within all adult tissues is an area of much intense ongoing research.  Understanding the mechanisms underlying the regulation of these stem cells has led to many recent breakthroughs in the field of cancer biology.  A recent paradigm-shift in cancer biology was the discovery that cancer is a disease resulting from dysregulation of adult stem cells.  The clinical implications of this concept are still being explored.  Obviously, there is still much in this field that remains unknown.