EMBRYONIC STEM CELLS derived from preimplan—tation embryos are undifferentiated cells capable of differentiation into derivatives of all three embryonic germ layers. These cells are also capable of self—renewal and have an almost unlimited developmental potential.

Embryonic stem cells are derived from the inner cell mass of a preimplantation blastocyst about five days postfertilization.

During the last decade, there has been ongoing research into the isolation of inner cell mass (ICM), as it is useful in establishing embryonic stem cell lines, which in turn have the ability to develop into most of the specialized cells in the human body, including blood, skin, muscle, and nerve cells. They also have the capacity to divide and proliferate almost indefinitely in culture.

The method for establishing a human embryonic stem cell line ...