But the articles describing the research have not yet been accepted for publication, an important step in the validation of scientific claims. Biologists believe embryonic cells hold great promise for restoring damaged tissues, particularly in otherwise intractable diseases like Alzheimer's and Parkinson's. Embryonic stem cells differ from adult stem cells, which are found in the various adult body tissues they help maintain. This week, a different group of researchers said it had isolated adult stem cells from fat tissue. But adult stem cells, which also offer a promising way of repairing damaged tissues, differ in many ways from embryonic stem cells.
Biologists are eager to explore both.
The Anthrogenesis scientists believe that they have found a possible new source of embryonic stem cells, though they cannot yet prove that their cells are embryonic in nature. The two known sources of embryonic cells are the blastocyst, a hollow sphere of cells produced a few days after an egg is fertilized, and fetal tissues that hold the future germ cells of the ovary and testis. Within the blastocyst is a clump of cells known as the inner-cell mass, from which all the tissues of the fetus are generated. Some of these cells migrate to the ovary and testis and can be recovered from fetal tissue. Known as embryonic germ cells, they closely resemble the embryonic stem cells that can be derived from the inner-cell mass.