Israeli scientists have for the first time successfully developed embryos from eggs taken from frozen, thawed and transplanted ovaries. So far, the procedure has been carried out in sheep only, but the research team is optimistic that it could one day be used in humans.

The team at the Institute of Animal Science in Israel attempted to freeze, thaw and transplant ovaries from eight healthy sheep. (Apparently sheep ovaries are very similar to human ovaries.)

Five of those transplants were successful, and of those, two went on to produce eggs, the BBC reports.

Lead investigator Dr Amir Arav said: "We have been able to demonstrate long-term intact cryopreservation with restored functioning following thawing and transplantation, in a large animal for around 36 months post-transplantation."

The research, published in the journal Human Reproduction, could eventually offer fresh hope to women slated to undergo treatments for cancer that would threaten their fertility.

Options currently available to women in these circumstances include fertilising and freezing eggs, or transplanting strips of their own ovarian tissue. Neither procedure has an especially high success rate, and researchers have long wondered whether whole ovary transplants might not be a better idea.

The research team says that there is a lot of work to do, but it hopes "it will not take more than a few years" for ovary transplants to become a clinical reality. ®