The world remains in serious disarray over stem cells. The spotlight this week has been on the US, where Congress unfortunately failed to override the first veto of George W. Bush's presidency; legislation that would expand federal funding of embryonic stem cell research is dead, at least until after the autumn's mid-term elections. Next week the focus will turn to the European Union, where science and industry ministers meet on Monday to decide whether the EU can continue to give limited grants for human embryo research.

On both sides of the Atlantic, public support for embryonic stem cell research has been growing, as people come to appreciate the medical benefits that could flow from the work - including treatments for conditions from Parkinson's and spinal injury to diabetes and heart failure. But a powerful "pro-life" minority remains implacably opposed to any experimentation with human embryos, even when they are still a microscopic ball of undifferentiated cells and even when in vitro fertilisation centres would otherwise discard them as surplus to requirements.