A scientist has achieved a world first... by cloning himself.
In a breakthrough certain to provoke an ethical furore, Samuel Wood created embryo copies of himself by placing his skin cells in a woman's egg.
The embryos were the first to be made from cells taken from adult humans.
Although they survived for only five days and were smaller than a pinhead, they are seen as a milestone in the quest for treatments for diseases such as Alzheimer's and Parkinson's.
But critics fear the technology could be exploited by mavericks to clone babies and accused the scientists of reducing the miracle of human life to a factory of spare parts.
The unmarried father of two, who is in his forties, is working on extracting stem cells from such embryos - a process that inevitably leads to the death of the embryo.
John Smeaton, of the Society for the Protection of Unborn Children, said: "We have got scientists wandering around in an ethical wilderness, forgetting about matters of justice relating to our fellow human beings.
"We have people creating human beings with the intention of destroying them. That's appalling."
And the Vatican condemned the cloning of human embryos, calling it the "worst type of exploitation of the human being".
"This ranks among the most morally illicit acts, ethically speaking," said Monsignor Elio Sgreccia, president of the Pontifical Academy for Life, the Vatican department that helps oversee the Church's position on bioethics issues.
Stem cell experts gave the U.S. breakthrough, published in the journal Stem Cells, a cautious welcome.
Professor Robin Lovell-Badge, of the Medical Research Council's National Institute for Medical Research, said: "This is another step along what has turned out to be a tortuous road.
"However, it is still a long way from the goal of achieving embryonic stem cells."
U.S. researcher Professor Robert Lanza questioned the validity of the research and said the embryos looked "very unhealthy".
Josephine Quintavalle, of the campaign group Comment On Reproductive Ethics, said: "Human cloning is unethical, unsafe, and completely unnecessary.
"It is time that scientists started to put some brakes on."
Dr Calum MacKellar, of the Scottish Council on Human Bioethics, said the creation and destruction of human embryos was "extremely offensive to millions in the UK".
Although Dr Wood's team is the first to create human embryos from adult cells, human embryos have been cloned before.
Scientists at Newcastle University created cloned human embryos in 2005 using cells from embryos rather than adults, seen as less useful in creating potential treatments.
British law says created embryos must be destroyed in 14 days and cannot be implanted in a woman.
I guess I'm not sure why scientists are hell bent on going this direction. There are other avenues for stem cell research other than going down the embryonic path. Personally, I think cloning leads us down the slippery slope to opening up all kinds of bizarre possibilities. I even worry that there are egomaniacs out there who are looking to take over God's role as Creator and re-vamp His design of the human body. Color me paranoid, but the whole cloning thing kinda freaks me out.