Scientists have created early stage sperm cells from the skin of men with a genetic defect that makes them infertile.
Scientists believe in the long-term future the technique may bring new hope to men genetically unable to generate sperm.
The process saw the skin samples from three men effectively sent backwards through the developmental process until they assumed the properties of embryonic stem cells - which can grow into virtually any kind of body tissue.
Dr Reijo Pera, lead researcher from Stanford University in the US, said his team's breakthrough might mean it is possible in future to "transplant stem-cell-derived germ cells directly into the testes of men with problems producing sperm".
British scientists have discovered an elusive protein that forms an essential part of human fertilisation.
The molecule, named Juno after the Roman goddess of fertility, allows eggs and sperm to join together.
It may now be used by scientists to improve fertility treatments and develop new contraceptives.
"We have solved a long-standing mystery in biology by identifying the molecules displayed on all sperm and egg that must bind each other at the moment we were conceived," said lead researcher Dr Gavin Wright, from the Wellcome Trust Sanger Institute in Cambridgeshire.
"Without this essential interaction, fertilisation just cannot happen," he added, writing in the journal Nature.
Fertility expert Dr Allan Pacey, from University of Sheffield, described the finding as "very exciting".
The Family Planning Association has said women should not "panic" over their ability to conceive as they reach their thirties.
Spokeperson Natika Halil, told the Daily Telegraph:
The comments came as England's Chief Medical Officer expressed concern about the number of women choosing to postpone motherhood until their late 30s and early 40s.
England's Chief Medical Officer has voiced concern about the number of women choosing to delay motherhood until their late 30s and early 40s, The Daily Telegraph reports.
Professor Dame Sally Davies reportedly told a group of health professionals on Thursday:
“The steady shift to have children later, there are issues with that. We all assume we can have children later but actually we may not be able to.
Prof Dame Sally added that she was “lucky” to have had two children in her 40s.
However, she also emphasised that she was not suggesting women should have children earlier, saying “It’s not for me to tell women what to do".
The chief medical officer's comments come as figures from the Office for National Statistics show that 1 in 5 women now reach the age of 45 without having children.
Several fertility experts have warned women to be cautious in their hopes after an woman's ovaries were 're-awakened' leading to her delivery a healthy baby boy in December.
Dr. Sherman Silber of the Infertility Center of St. Louis criticized the approach, saying he has had success by using drugs rather than surgery to treat the condition. He also disagreed with the researchers' explanation as to why this treatment worked.
The new results, experts cautioned, must be viewed as preliminary.
"It shows a lot of promise (but) I don't think it's even close to being ready" for routine use, said Dr. Mark Sauer of the Columbia University Medical Center in New York. Dr. Amber Cooper of Washington University in St. Louis called the technique "very much an experimental method."
It is a fairly amazing process, and so far has been 100% successful in producing one child in Japan so there is one very satisfied customer.
Some women stop producing eggs early on, like the patient in Japan, but now it seems that these follicles can bereawakened.
The process is quite complicated - they remove some of the ovary through keyhole surgery, they then cut it into tiny little bits because there is a natural mechanism in the ovaries that stops them producing too many eggs at once.
By cutting it up you overcome that mechanism, they also give it a drug which switched off a mechanism which stops the follicles developing into eggs.
They then put them back into the woman, give her hormonal treatment to mature them and then take them out and use a conventional IVF treatment to produce a baby.
It is very early days yet, as the researchers admit, but it looks like it could be promising for some women.
Scientists at Stanford University of Medicine have developed a radical new treatment to stimulate egg production in infertile women who suffer from 'primary ovarian insufficiency' a condition that causes early menopause.
Dr Aaron Hsueh and Yuan Cheng, who made the discovery, explained their work in a video produced by Stanford University.
The scientists said the treatment could be a "real breakthrough" in treating infertile women, but that more studies, particularly on women whose infertility is caused by other factors, is needed.
A woman suffering from a condition called primary ovary insufficiency has given birth to a healthy baby after taking part in a pioneering study and clinical trial.
Using a technique called IVA ("in vitro activation") researchers removed the woman's ovaries, treated them outside the body, and re-implanted them near her fallopian tubes. The woman was then treated with hormones to stimulate the ovary follicles in which eggs develop.
Although the method was developed specifically for women suffering from primary ovary insufficiency, the researchers at Stanford University plan to investigative whether the technique can be used to treat other types of infertility.
A woman has given birth to a baby after having her ovaries "reactivated" through a new technique developed in Stanford University in the US and St Marianna University School of Medicine, Japan.
Doctors in the US and Japan developed the technique to remove the ovaries, activate them in the laboratory and re-implant fragments of ovarian tissue.
The technique, reported in Proceedings of the National Academy of Sciences, has resulted in one baby being born, whilst another is expected.