Australian researchers said today they may have found a way to fertilise an egg with cells from any part of the body, rather than sperm.
Australian infertility scientist Ms Orly Lacham-Kaplan said early research on mice could produce a breakthrough for many men who have no sperm or sperm-making cells.
"This is the group for which this kind of technique probably will be very helpful," she said. "A lot of [these] people would like to father their own biological children".
Ms Lacham-Kaplan said the research, if successful in humans, could also theoretically allow babies to be born without any male input, although she said this could open up an ethical can of worms.
The mice experiments were expected to take up to a year.
If they are successful - and Ms Lacham-Kaplan admits to some doubts - then it will be possible to experiment on humans, although where such trials could take place would be limited.
Australia, like many other countries, has banned all experiments involving somatic cell transfer into human eggs, but the United States could be an option, she said.
"At the moment I feel there will be more problems than success, but if it is a success, it will be quite a good surprise", she said. "It would be an incredible breakthrough".