British scientists have produced human sperm from stem cells. According to the BBC, a team of researchers at Newcastle University announced on Tuesday they created sperm with stem cells extracted from a five-day-old male fetus in to which they injected retinoic acid and other chemical substances.

Prof. Karim Nayernia, who led the research, said microscopic observation of the artificially produced sperm showed that these sperms were in par with natural sperm in terms of mobility and functionality.

This could be a breakthrough in the treatment of male infertility. There were some controversial reactions, with critics saying women will now be able to get pregnant without men, but at the current level of research, sperm can be made only with men's XY stem cells.

The work might lead to fertility treatment in five to 10 years, Nayernia told the Financial Times, as more research is needed to use "in vitro designed" sperm to fertilize human eggs. The results are published in the latest edition of Stem Cells and Development.