Now, scientists create artificial sperms, eggs

For the first time, scientists have created primordial germ cells — cells that will go on to become egg and sperms — using human embryonic stem cells.

Although this had already been done using rodent stem cells, the study, published in the journal Cell, is the first time this has been achieved efficiently using human stem cells. The project was undertaken by experts at the University of Cambridge and the Weizmann Institute.

"The creation of primordial germ cells is one of the earliest events during early mammalian development," says Dr Naoko Irie, first author of the paper from the Wellcome Trust/Cancer Research UK Gurdon Institute at the University of Cambridge. "It's a stage we've managed to recreate using stem cells from mice and rats, but until now few researches have done this systematically using human stem cells. It has highlighted important differences between embryo development in humans and rodents that may mean findings in mice and rats may not be directly extrapolated to humans." Azim Surani at the Gurdon Institute, who led the research, and his colleagues found that a gene known as SOX17 is critical for directing human stem cells to become PGCs (a stage known as 'specification').

The release added that this was a surprise as the mouse equivalent of this gene is not involved in the process, suggesting a key difference between mouse and human development.

SOX17 had previously been shown to be involved in directing stem cells to become endodermal cells, which then develop into cells including those for the lung, gut and pancreas, but this is the first time it has been seen in PGC specification.