MEDICINE
Doctors make embryos in a new way
Scientists have for the first time managed to create a large quantity of embryos with neither egg nor sperm cells. The scientists, from Maastricht University in the Netherlands, extracted two different types of stem cells from pregnant mice. One type is responsible for the development of the placenta, whereas the other is the source of the embryo itself. The scientists made the cells divide separately, until they had a major quantity of both, and placed them in the same culture dish. Much to their surprise, the stem cells organised into tiny embryos. About 10 of the embryonic cells huddled together and were surrounded by placenta cells. According to the scientists, the two types of cells somehow communicate.
The scientists implanted some of the new embryos into mice to see what would happen. The embryos grew for a few days, and the mice showed signs of pregnancy, but after about 3.5 days, development stopped. Scientists do not yet know why. With the availability of many identical embryos, scientists can subject them to different environmental influences and find out why some pregnancies go wrong. They may also discover why fertility treatment, by which eggs are implanted, only have a success rate of about 25 %.