Stem cell success in Japan could create artificial sperm and eggs from male or female cells.
Ground-breaking new stem cell research is paving the way for two gay men or women to conceive a child together.
Scientists at the University of Kyoto experimenting with mice were able to artificially create eggs from stem cells that produced healthy offspring, a study published in Science showed.
The break-through has the potential to help infertile women conceive and allow gay couples to combine their DNA to create a child biologically parented by both of them.
Scientists have previously struggled to create sex cells from stem cells, Nature science journal reported last week.
The lab headed by Mitinori Saitou at Kyoto University successfully created sperm from stem cells last year and have now created eggs. They are now working on the same experiment with human cells.
Dr Katsuhiko Hayashi, from Kyoto University, said to the BBC:
'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.'
Hank Greely, a bioethicist at Stanford University, said (The Advocate reported):
'There are lots of lesbian and gay couples who would be very excited about the possibility for the first time of being able to have children who are genetically their own.'