Precursors of human sperm and eggs made from stem cells

Guest post by Tina Hesman Saey

Human stem cells  can produce germ cells, precursors of egg and sperm cells, in laboratory dishes.  Researchers have coaxed both embryonic stem cells and reprogrammed adult cells to become human germ cells.

Scientists have already produced viable eggs and sperm from reprogrammed mouse cells, but the mouse recipe was no help to researchers trying to coax human cells to make the reproductive cells. A protein called SOX17 is essential to produce human germ cells but plays no role in making mouse egg and sperm precursors, developmental biologist Azim Surani of the University of Cambridge and colleagues discovered. The finding appears December 24 in Cell.

That and other fundamental differences between early human and mouse embryos could mean that studies of early development should be conducted on laboratory organisms that more closely mirror humans, Surani says. “Extrapolation from work on mice to early human development may need to be reconsidered.”