The information accrued to date regarding embryonic development and stem cells have been accumulated from basic research on mouse embryonic stem cells. Since 1998, researchers have succeeded in culturing human embryonic stem cells under laboratory conditions. Human embryonic stem cell lines have been established from the inner cell mass of human blastocysts that were produced through in vitro fertilization procedures. The techniques for growing human embryonic stem cells as described earlier, are similar to those used for culture of mouse embryonic stem cells. However, human embryonic stem...