Professor Karim Nayernia, is seen at Newcastle University and the NorthEast England Stem Cell Institute (Nesci), in Newcastle, England. (AP)
Is this a major breakthrough? Or could it be just another controversial claim that might not stand the test of time?
Scientists in Britain claim to have created human sperm using stem cells in a technique that could revolutionise fertility treatment.
Researchers at Newcastle University say they used a new technique to derive sperm cells from embryonic stem cells.
Stem cell expert Professor Karim Nayerina says: "In future we hope to isolate the skin cells turn them to the stem cells and from those stem cells we could generate sperm cells."
But not everyone is convinced, and the claims are now being questioned.
Says Dr Allan Pacey, senior lecturer in Andrology, University of Sheffield: "There's quite an elaborate series of events that occurs when a sperm meets an egg and the chromosomes merge together and I would want to see that as another piece of crucial evidence to make sure that what we have here are actually sperm."
It has also brought the spotlight back on one of the biggest medical controversies in recent year -- creating life in a laboratory
Says human genetics Dr David King: "One thing that might be done with this is that it opens the possibility of genetic modification of human beings. So you can see that it opens the possibility of opening all kinds of avenues that I really think we shouldn't go down."