John Parrington examines the controversy over the cloning of human embryos.
A controversial area of science that has hardly been out of the spotlight since the birth of its leading lady - Dolly the sheep - is cloning. The recent announcement that scientists have succeeded in cloning a human embryo has reignited the simmering debate about the issue. The US biotechnology firm responsible, Advanced Cell Technology (Act) says its intention is not to produce a cloned baby. Instead it aims to produce cloned embryos as a source of human stem cells. These have the unique property of being able to mature into any cell type in the body.