Life from Stem Cells
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In Henry Greely's book The End of Sex and the Future of Human Reproduction, the professor claims that humans will soon be able to create their own eggs grown from skin cells. Then, based on their genetic makeup, parents can decide which eggs they want to fertilize and develop into children. Well, it turns out the "end of sex" Greely was talking about may be coming sooner than we expected - scientists have created the first synthetic mice embryos using stem cells rather than a sperm and egg, and successfully implanted them into wombs.

The research was meant to investigate the crucial part of pregnancy that happens when an egg develops into a blastocyst: the thin outer sphere of cells that will become the placenta, and a tiny inner sphere of cells that will become the embryo. The scientists found that the stem cells, when properly assembled, will independently organize themselves into an embryo and blastocyst combination (called a blastoid).

According to Nicolas Rivron, one of the authors of the new study: "In a natural embryo, those same stem cells are in three dimensions talking to each other in a language that we barely understand... The embryonic cells were the chatty ones here - they are instructing the placental stem cells to multiply, organise and implant into the uterus."

This is an important moment in fertility science. The failure point for around two-thirds of in-vitro fertilization (and many miscarriages) occurs when the fertilized egg doesn't implant itself in the uterus, and it's still unclear why this happens. With a newfound ability to grow unlimited artificial embryos, scientists now have a lot more room to experiment, says co-author Clemens van Blitterswijk: "We can create large numbers of model embryos and build up new knowledge by systematically testing new techniques and potential medicines."

Right now there's no plan to apply this technology to humans, but the potential to create unlimited human embryos opens up all kinds of ethical issues - from designer babies, to choosing which fertilized eggs get to become children. It's the Sophie's Choice of genetics, and there's no precedent for right versus wrong. Hopefully by the time these questions demand answers, medical technology will have rendered them obsolete.

Who knows, maybe one day we'll be able to "grow" our early ancestors in a lab, Jurassic Park-style.