The adult stem cells extracted from the placenta are called amniotic epithelial cells. These cells may become useful in fighting diseases and disorders of degenerative diseases while avoiding the controversy surrounding embryonic stem cells. In harvesting embryonic stem cells, a human embryo is destroyed. Many pro-life individuals associate this act with abortion and consider it immoral. As the placenta is commonly discarded after birth, the ability to harvest stem cells from these non-controversial sources may come to represent a major innovation in stem cell research. Amniotic stem cells, unlike embryonic stem cells, have failed to show a propensity for developing into teratomas and other cancer-like tumors upon injection into living tissue. Another potential benefit of using amniotic stem cells over those obtained from embryos is that they side-step ethical concerns among pro-life activists by obtaining pluripotent lines of undifferentiated cells without harm to a fetus or destruction of an embryo.