How are embryonic stem cell lines created?
Embryonic stem cells are derived from spare embryos donated by couples undergoing in vitro fertilization (IVF) treatment. In IVF, just as in natural conception, not every fertilization event results in an embryo that will develop to term. Therefore, spare embryos are routinely produced during IVF to help ensure a successful outcome. When a healthy pregnancy is achieved, the spare embryos are saved in cold storage for a period of years, after which they are discarded. If the couple agrees, however, the embryos may be used to create stem cell lines. The spare embryo develops in a petri dish for about five days post-fertilization, at which stage it becomes a blastocyst. The blastocyst is a round ball of cells that would fit on the head of a pin. None of the specialized tissues of the body have begun to form at this stage of development, but within the ball is a small clump of cells called the “inner cell mass.” These primitive cells will give rise to all the cell tissues and organs of the
