Before now, scientists had only succeeded in doing so with the eggs of mice, maturing those eggs to the stage where they produced living babies. They had also grown human eggs from a later stage of development.
Scientists at two research hospitals in Edinburgh, Scotland and the Center for Human Reproduction in New York completed this latest experiment. They published the results of their research in the journal Molecular Human Reproduction in early February.
They said this research could one day help in developing medicines and new treatments for people who are unable to produce children.
Normally, microscopic eggs develop in the part of the female reproductive system called ovaries. However, this is the first time human eggs have been developed outside the human body from their earliest stage to full maturity.
Evelyn Telfer is a co-leader of the research. She told the Reuters news service, "Being able to fully develop human eggs in the [laboratory] could widen the scope of available fertility treatments. We are now working on optimizing the conditions that support egg development in this way and studying how healthy they are."
Independent experts not directly involved in this work supported it by calling it important. But they also warned that there is much more to do before laboratory-grown human eggs could be safely made ready for reproduction with sperm.
Ali Abbara is a medical expert at Imperial College London. He said this latest research suggests it may be possible to fully combine human eggs and sperm outside the body in the future.
"[But] the technology remains at an early stage," he added. "And much more work is needed to make sure that the technique is safe and optimized before we ascertain whether these eggs remain normal during the process, and can...form embryos that could lead to healthy babies."
Darren Griffin is a genetics professor at Kent University in the United Kingdom. He called the work a surprising technical success. If success and safety rates were improved, it could help future cancer patients receiving chemotherapy treatment protect their fertility, said Griffin. It could also improve fertility treatments, and deepen scientific understanding of the biology of the earliest stages of human life.
I'm Pete Musto.