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Embryonic stem cells can differentiate into the three "germ layers": [[ectoderm]], [[endoderm]] and [[mesoderm]].  The 220 types of cells in humans are all based on these germ layers.  Some scientists have shown effectively that embryonic stem cells have greater differentiation potential, and divide into greater numbers, than [[adult stem cells]] can.

Embryonic stem cells can differentiate into the three "germ layers": [[ectoderm]], [[endoderm]] and [[mesoderm]].  The 220 types of cells in humans are all based on these germ layers.  Some scientists have shown effectively that embryonic stem cells have greater differentiation potential, and divide into greater numbers, than [[adult stem cells]] can.

In 2001 President [[George W. Bush|Bush]] allowed [[federal funding]] for research performed only on 60 strands of already existing stem cells. <ref>http://www.whitehouse.gov/news/releases/2001/08/20010809-2.html </ref>. Despite the strong genetic similarities no work was done on Chimp stem cell lines.

In 2001 President [[George W. Bush|Bush]] allowed [[federal funding]] for research performed only on the 60 human embryonic stem cell lines that were in existence at the time<ref>http://www.whitehouse.gov/news/releases/2001/08/20010809-2.html </ref>. Cell lines drift genetically and morphologically over time, and due largely to the ban on producing more embryonic stem cell lines with NIH funds, researchers focused on producing embryonic-like stem cells from adult (differentiated) cells; these cells are known and induced pluripotent stem cells (iPS cells). These cells have similar properties to embryonic stem cells but do no require the destruction of or any use of human embryos - humans donate their own cells (e.g. skin cells) and though slight genetic manipulation these cells, they can be reverted into essentially an undifferentiated state and gain the ability to become nearly any cell in the body (i.e. pluripotency). This major advance in the stem cell and medical fields came much sooner than most researchers expected; this can be credited largely to the Bush ban regarding human embryonic stem cells.

 

Despite the strong genetic similarities, the production of chimpanzee stem cell lines have been problematic, though stem cells have been produced for other non-human primates.

==Controversy==

==Controversy==