Both egg and sperm cells start life as primordial germ cells (PGCs). Last year, Katsuhiko Hayashi and his colleagues at Kyoto University in Japan found they could generate PGC-like cells from either mouse embryonic stem cells or body cells that can turn into stem cells – known as induced pluripotent stem cells or iPSCs.
What’s more, the team managed to coax these PGC-like cells into becoming sperm.
Now Hayashi and his colleagues have created eggs from the PGC-like cells.
They started with embryonic stem cells and iPSCs taken from a female mouse embryo. In separate experiments, the team coaxed each type of stem cell to form PGC-like cells. When these cells were surrounded by ovary cells, also taken from a mouse embryo, they formed immature egg cells. The team implanted these young egg cells into the ovaries of adult mice.
Four weeks later, when Hayashi’s team removed the ovaries, they found the cells had developed into mature eggs. When these eggs were fertilised with sperm and implanted into other mice, they were able to form embryos that developed into healthy mouse pups.
…Once the wrinkles have been ironed out, it would be possible, in theory, to fertilise stem-cell-derived eggs with stem-cell-derived sperm, Telfer says. “If you took the stem cells from the same individual you could avoid sexual reproduction.”