Eggs from embryos breakthrough

US scientists have managed to grow egg cells from early mouse embryo cells, an achievement that has implications for research into stem cell therapies and infertility. The researchers, based at the University of Pennsylvania in Philadelphia, found that embryo cells grown in the laboratory could be coaxed into making eggs and egg-nurturing cells similar to those found in the body. Their findings, described as 'very important, very impressive research' by UK developmental geneticist Wolf Reik, were published in the journal Science last week.

Stem cells found in early embryos are capable of turning into a wide range of different body tissues, a property that researchers are hoping to harness to develop therapies for human diseases. But until now, 'most scientists have thought it impossible to grow gametes from stem cells outside the body', says lead researcher Hans Scholer. His team found that not only did mouse embryo stem cells produce egg cells, but they also began to divide, multiply and recruit other cells to form egg-nurturing structures called follicles. If the eggs are found to be normal, and can be produced efficiently, then they could be used for research into female infertility, embryo development, and perhaps for generating cloned body tissues. However, Scholer stresses that 'cloning to generate organisms, be they mouse or humans, is a dead end', saying that 'I see this approach as a source of interesting stem cells'.

Scholer now wants to find out if the laboratory-produced eggs can be fertilised with mouse sperm to make healthy embryos. He hopes that eventually the process can be repeated in primates and other species, to enable research into possible therapeutic applications. 'The process in mice is so simple I don't see a reason it wouldn't work with primate embryonic stem cells' he said.