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#18
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Women don't become pregnant and then have their baby aborted to supply stem cells. That would be scientifically impossible. The cells would already have become differentiated long before the time that the embryo attaches to the uterine wall. The value of stem cells is that they have not become differentiated, that is... they haven't become nerve, heart, mucscle, etc tissue. Stem cells (undifferentated cells) come into existance at the early stages of development, stage eight mitosis. This is when the fertilized ovume has divided eight times. At that point, it is a cluster of cells called an embryo. At the next stage of mitosis (cell division), a tube develops that will later become the heart. Next comes the beginnings of neural tissue. The stage of development that holds promise is before this occurs. Embryos are created in a petri dish, outside of the donor female, for implantation. Eggs are harvested and fertilized invitro. The surplus have been stored in liquid nitrogen should the need for reimplantation occur. Those that aren't needed are stored until they are no longer viable, then discarded. Last edited by Downthestretch55 : 07-20-2006 at 11:43 AM. |