Human embryos in medical research
Embryonic stem cell research is the utilization of stem cells from embyros which can then be grown laboratory culture and produce specialized cells supposedly to treat diseases or used for research purposes. A common source of such cells is discarded embryos at fertility clinics. The use of embryonic stem cells in medicine has met with some controversy, particularly from the pro-life movement that is concerned about the destruction of embryos that they believe constitute human lives.
Adult stem cell research is similar except it does not use or destroyed embryos, and instead is based on stem cells that can be taken from adults. These cells so far have proven less potent than those harvested from discarded embryos, but they do not raise the associated ethical dillemas.
Arguments for and Against Embryonic Stem Cell Research
A variety of arguments are used both for and against embryonic stem cell research. Some proponents argue that the embryos do not constitute human lives or that even if they do since the embryos would be destroyed anyways and thus it makes sense to use the embryos.. These arguments have been accepted by some Christian groups and by many Jewish groups, even Orthodox ones..
Opponents to such research have argued that such embryos are human lives with the full rights of humans and that even if they are not human lives the slippery slope is too great. Furthermore, they argue that the sanctity of human life is so great that even the destruction of such embryos for research is not permissible even when they would be destroyed anyways. Opponents have also argued that the potential of embryonic stem cells have been exaggerated and that more research must be done with cord and adult stem cells.  .
An alternative approach would be to use parthenogenesis, the term that's applied to an egg that activates spontaneously on its own. This is relatively common in women. Eggs activate and often form cysts or benign tumors in the ovary. Those activated eggs begin to divide, and they look like embryos at the early stages. They form blastocysts with stem cells inside. A young woman with Type 1 diabetes could donate her eggs, which could be activated artificially in the laboratory without being fertilized. When the eggs develop to the blastocyst stage, her own stem cells could be used to treat her Type 1 diabetes.
Stem cells developed from an unfertilized monkey egg that went through parthenogenesis are being used to treat Parkinson's disease in monkeys. This line has proven to be as robust as stem cells from human eggs.
One of the reasons this line of research has not been pursued is that in the Dickey Amendment that was put in place by Congress in 1996, parthenogenesis was specifically included with the rest of embryo research, so scientists cannot get federal funding to do work even on unfertilized human eggs.