Currently, under UK law, it is illegal to create artificial sperm and egg cells using stem cells in order to produce a baby, say for an infertile or homosexual couple. But new "hugely exciting" research from Japan has found a potential way around this law.
The research, led by Dr Katsuhiko Hayashi from Kyoto University, involved taking stem cells from early-stage mouse embryos and turning them into cells that are a precursor to sperm cells, known as primordial germ cells (PGCs).
The PGCs were then transplanted into newborn mice which did not have their PGCs. Once transplanted, the cells produced normal-looking sperm.
These sperm were used to fertilise eggs and, as a result, healthy male and female baby mice were born, which were capable of reproduce normally.
Dr Allan Pacey, a senior lecturer in andrology at the University of Sheffield, explained that since the new research did not create artificial sperm, but instead cells that grew into sperm, it could potentially be a treatment used legally in the UK.
He said: "Under UK law you would not be allowed to use an artificial gamete (a sperm or egg). The philosophy of the law is to stop that kind of thing happening. But in this case you're not technically creating sperm, so it might be that you can side-step this regulation. It all depends on definition.
"This is quite a step forward in developing a process by which sperm could be made for infertile men, perhaps by taking as a starting point a cell from their skin or from something like bone marrow.
"Clearly more work needs to be done to refine this process, but it's hugely exciting."
When asked if there were any ethical reasons against using the research to treat infertility, Dr Pacey said: "If it is safe, no."