Human embryo research: ethics and recent progress.
This review evaluates recent developments in the application as well as legalization of human embryo research. A number of European countries, including the United Kingdom and Spain, have recently enacted comprehensive legislation to regulate embryo research. Research reviewed here was conducted either with the aim to alleviate certain medical conditions or to improve the low success rates of assisted reproductive technology. Research was usually conducted on embryos that were considered unfit for immediate transfer or unsuitable for cryopreservation. Research projects were aimed at 1) studying the metabolism of the embryo, 2) promoting embryonic viability, 3) assisting fertilization in patients with fertilization disorders, and 4) determining gene disorders in embryos from couples at risk for transmitting genetic disease.