Good eggs

摘要

This year's Nobel prize for medicine went to Sir John Gurdon and Shinya Ya-manaka (both pictured above) for a crucial discovery in · stem-cell science: how to make what are known as pluripotent stem cells from ordinary body cells. What the citation did not say was that this work also allows clones to be made from adult animals, potentially including people. A stem cell is one that can differentiate into daughter cells specialised for particular functions, and all the cells in a body are thus derived from stem cells. That includes the stem cells themselves, which derive from "ur" stem cells found in embryos.