Okay, this is a big deal. A research team from Kyoto University has successfully used both murine stem cells and murine induced pluripotent stem cells to generate functioning oocytes. For those of you who do not excel in Latin, that means they took mouse embryonic stem cells and some ordinary mouse cells, and developed each into eggs. Those eggs were then used to create healthy mouse offspring.
This team and others have created both sperm and eggs from stem cells before, but haven't been able to produce healthy offspring from them. This time the researchers used proteins and other factors to induce the stem cells and iPS cells into becoming "primordial germ cell-like cells," or PGCLCs. The PGCLCs were then combined with cells from mouse ovaries to make artificial ovaries. These were then transplanted into female mice. After a month, the mice were found to be carrying immature eggs. The eggs were matured in vitro and then fertilized; the resultant embryos were transferred into female mice, who then gave birth. The happy mothers later became grandmothers, without need for further laboratory intervention.
Making oocytes out of stem cells would be impressive enough, but making them out of iPS cells is huge. This lab took an ordinary cell from a mouse, tweaked it and coaxed it into becoming an oocyte, and then made a baby mouse out of it. We're that much closer to being able to do that same trick for humans.
So, any tissue sample from any person, dead or alive, could in theory be used to make that person's baby. Did I say this was a big deal? Obviously it opens up some amazing possibilities for infertility treatment; but obviously, also, it poses huge challenges for control over the future uses of tissue in research and in the clinic.