However, many experts say that not only scientific but ethical hurdles must be overcome, putting a damper on what was thought to be a brilliant solution toward infertility problems for many couples.
Japan's Kyoto University
has previously made viable sperm from stem cells. With their new egg experiments, it is shown that stem cells have the ability to become any other type of cell in the body --- from nerves to skin, blood to bone.
The university used stem cells from two sources: those collected from an embryo and from skin-like cells which were scientifically reprogrammed into stem cells. The stem cells were then developed into early versions of eggs. A "reconstituted ovary" was then made by surrounding the early eggs with supporting cells, normally found in an ovary, before transplanting them into female mice. This environment helped the eggs mature .
The eggs were then collected with an IVF technique, followed by fertilization from a male mouse before being implanted into a surrogate mother mouse. Dr Katsuhiko Hayashi, from Kyoto University, told the BBC: "They develop to be healthy and fertile offspring. They then had babies of their own, whose 'grandmother' was a cell in a laboratory dish."
Reconstitution of female germ-cell development in vitro is a key challenge in reproductive biology and medicine, according to Science
Numerous scientists are impressed by Japan's experiments with stem cells, but are doubtful about using it for many reasons. Dr. Hayashi himself said that their experiment was still a distant prospect: "I must say that it is impossible to adapt immediately this system to human stem cells, due to a number of not only scientific reasons, but also ethical reasons."
Dr. Hayashi felt that the level of understanding was still too limited about the human egg development and not enough information was known about long-term consequences on the health of any resulting child.
Dr Evelyn Telfer, from the University of Edinburgh, said, "If you can show it works in human cells, it is like the Holy Grail of reproductive biology."