Scientists can make human eggs from male embryos
By Roger Highfield, Science Editor

The ability to make an endless supply of human eggs for post-menopausal women - even for men - could emerge from a breakthrough in reproductive science published today.

Scientists have found a way to mass produce eggs from embryos, even male embryos, a technique that could scrap the "biological clock" of women, end the shortage of eggs for infertility treatments and remove one of the reasons given by maverick doctors for cloning babies.

However, the American research also makes it feasible for men to make eggs too so that it will be possible, in theory, for a homosexual male couple to have children that are genetically their own, with the help of a surrogate mother.

Although it seems likely a similar approach could also help infertile men to make sperm, the technique will not enable women to make sperm because they lack a Y chromosome, the "maleness" chromosome (men do have one X chromosome, the sex chromosome possessed by women, so they can make eggs).

One professor of theology called the work "a cannon ball fired across the bow of Christian bioethics. Many still operate with the assumption that babies require a mummy and a daddy."

Prof Ian Wilmut, of the Roslin Institute, near Edinburgh, is excited by the implications for cloning because it undermines claims that it could be justified for infertility treatments.

"If the method can be adapted for use with human embryo stem cells, and to produce sperm from embryonic stem cells, this would be the end to calls that cloning should be used to overcome infertility," he said yesterday.

Instead, cloning would be used to create an embryo from an infertile person and then an egg or sperm as required, which in turn could be used for IVF treatments.

"In this way, both man and woman would contribute their genes to the child as they do normally," he said. The possibilities are raised today by Prof Hans Scholer's team at the University of Philadelphia which removed cells from early male and female mouse embryos, placed those stem cells in Petri dishes and grew them into eggs and then into embryos.

Reported in the journal Science, the work shows that, even outside the body, embryonic stem cells remain "totipotent," that is capable of generating any of the body's tissues, said Prof Scholer.

"Most scientists have thought it impossible to grow gametes (egg and sperm cells) from stem cells outside the body since earlier efforts have yielded only somatic (body) cells."

But his team found that not only can stem cells from mouse embryos produce eggs but also those eggs can then divide, recruit adjacent cells to form structures similar to the sacs - follicles - that surround and nurture natural mouse eggs and develop into embryos.

The American team now plans to test whether those eggs can be fertilised.

In the early 1950s, the American psychologist Solomon Asch performed an experiment to determine just how easily people cave in to peer group pressure. Those taking part sat alongside five other people, and were asked to judge the length of a line. Unknown to them, the five others were all accomplices of Asch, instructed to give a patently absurd answer. Yet such was the power of the peer group that 70 per cent of individuals taking part went along with the majority view.

Having endured yet another week of ballyhoo about the Human Genome Project, DNA and the double helix, my only doubt about Asch's findings is that his figure of 70 per cent may be too low. Certainly in the case of DNA, I doubt if one scientist in a hundred would dissent from the view that James Watson and Francis Crick discovered the Secret of Life in the double helix structure of DNA. Yet they didn't, and it isn't.

I should confess that until recently I too believed the scientific fairy story of James and Francis and the Secret of Life. What woke me from its spell was an article in the recent Nature supplement marking the 50th anniversary of the discovery of the double helix. It was written by Dr Maclyn McCarty, of the Rockefeller University, New York, the sole surviving member of a team led by Oswald Avery, the biochemist. By the end of the article, it was clear that Avery and his colleagues have been the victims of a truly shocking miscarriage of academic justice.

To explain why, consider this question: what led Watson and Crick to work on DNA in the first place? Since 1869 this rather boring molecule had been known to lurk in the central nucleus of cells, and was still regarded as boring when Watson and Crick began focusing on it 80 years later. The consensus was that the key to the Secret of Life - the rules governing all living cells - took the form of far more complex cellular chemicals known as proteins.

So what made Watson and Crick think otherwise? As both freely admitted in their biographies, it was the experiments of Avery and his colleagues. Working with strains of pneumonia bacteria, Avery's group found that it could extract a substance that compelled one bacterium to take on a trait of another - and then pass it on to its offspring. Whatever this substance was, it seemed to possess the attributes of "genes", the long-sought carriers of the instructions for life itself. But was it a protein or DNA?

In 1944, after years of careful work, Avery and his group published the first hard evidence that genes are made from DNA. If they were right, the group could claim to have identified the key to the Secret of Life. Not surprisingly, their results were given a very tough time. Critics pointed out that only one trait had been changed; others suspected that the DNA was contaminated. Clearly, more work was needed before Avery and his colleagues could be credited with having cracked the Secret of Life.

This is where Watson and Crick come in. With characteristic self-confidence, they ignored all the hand-wringing over Avery's results, decided he was right, and set about showing that DNA possessed the molecular structure suitable for the carrier of genetic information. As everyone knows, the double helix was triumphant vindication of their confidence in Avery's findings.

Others also found evidence to back Avery's claims for DNA. They included Alfred Hershey at the Carnegie Institute, New York, who used a clever radioactive labelling method to distinguish between protein and DNA in bacteria infected by viruses. Though much less compelling than Avery's original work or the double helix, Hershey's findings supported those from Avery's group - whose place in scientific history seemed assured.

At this point, however, the story of the Secret of Life takes a bizarre turn. Despite being vindicated by the brilliant work of Watson and Crick, the work of Avery and his colleagues was still treated with deep scepticism by the Nobel Committee - and by the time the quibbling stopped, Avery was dead. Being denied a Nobel is one thing; the fact that all those who confirmed his group's key insight - including Watson, Crick and Hershey - won Nobels leaves no doubt about the importance of Avery's original work.

The real scandal is the way Avery, who died in 1955, and his colleagues are still being denied their rightful claim to be the true discoverers of the Secret of Life by a Hollywood-style story about two wise guys called Watson and Crick and a pretty-looking molecule.

2 May 2003