An incredible medical breakthrough:

Scientists at the New York Stem Cell Foundation Laboratory have reprogrammed an adult human egg cell to an embryonic state using cloning technology and created a self-reproducing line of embryonic stem cells from the developing embryo. In so doing, they have managed a feat that has at times been thought impossible, then inevitable, then completed, then incomplete and unfeasible. Their work is published today in Nature1.

It is not the end-all experiment that scientists aiming to create embryonic stem cells have been hoping for — the embryos are not true clones, because the DNA of the stem-cell line does not match that of the patient who donated cells — but it is a step in that direction and addresses some of the problems that have flummoxed experiments.