The new technique would be performed on a two-day-old embryo, after the fertilized egg has divided into eight cells, known as blastomeres. In fertility clinics, where the embryo is available outside the woman in the normal course of in vitro fertilization, one of these blastomeres can be removed for diagnostic tests, like for Down syndrome.
The embryo, now with seven cells, can be implanted in the woman if no defect is found. Many such embryos have grown into apparently healthy babies over the 10 years or so the diagnostic tests have been used.
Up to now, human embryonic stem cells have been derived at a later
stage of development, when the embryo consists of about 150 cells. Both this stage, called the blastocyst, and the earlier eight-cell stage, occur before the embryo implants in the wall of the womb. Harvesting the blastocyst-stage cells kills the embryo, a principal objection of those who oppose the research.
Many believe (and I am one of them) that Embryonic Stem Cell research holds the key to curing many of todays diseases. The potential use of stem cells is limitless. Embryonic stem cells are by nature undifferentiated (a cell that has not yet generated structures or manufactured proteins characteristic of a specialized cell type) . That means that they can be used to replicated virtually any cell in the human body.
However, because the nature of harvesting the stem cells kills the embryo, the pro-life crowd is against it. President Bush has declined to extend federal funding to new stem cell lines. Will this new technique overcome the pro-life objections? That remains to be seen.
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