Human embryos have been created in the lab for the sole purpose of harvesting their stem cells for the first time.

Until now, scientists had derived stem cells only from excess embryos donated from infertility treatments. In this case, the scientists approached donors and informed them that their eggs and sperm would be used to develop embryos for stem-cell research.

The work, conducted by researchers at the Jones Institute for Reproductive Medicine in Norfolk, drew criticism from religious conservatives opposed to embryo research.