fetal tissue implant or fetal cell therapy, implantation of tissue from a fetus into a patient. In experimental procedures, fetal brain tissue has been implanted in the brains of patients with Parkinson's disease so that the fetal tissue will supply chemicals lacking in the diseased brain, but such therapy failed to show significant benefits in a controlled study. Because fetal cell therapy uses tissue from freshly aborted fetuses, the procedure is controversial. Both the Reagan and G. H. W. Bush administrations banned the use of federal funds for fetal-tissue research that used tissue from aborted fetuses. President Clinton lifted the ban early in his administration. The successful transplantation of eggs from fetal ovaries in experiments with mice led to the suggestion in 1994 that human fetal ovaries or eggs taken from such ovaries could be implanted in infertile women, a possibility that troubled many ethicists and others. Some fear the use of what they call "fetal farming," the conception in vitro or in vivo of embryos solely for their medical usefulness. Others point to the potential benefits in the treatment of Alzheimer's and Huntington's diseases, and possibly in cases of nerve injury.