A Minnesota woman with diabetes said she wanted to get pregnant, have an abortion, probably within the first three months, and then transplant insulin-producing islet cells from the fetus into her body in the hopes of curing her disease.

In another case, a California woman wanted to become pregnant through artificial insemination with sperm donated by her father, abort the fetus and transplant its brain cells into her father, who has Alzheimer's disease.

At an international conference on brain implants held last year in Rochester, N.Y., a New York City woman searched among participants for a surgeon to put fetal cells into the brain of her husband to treat his severe Parkinson's disease. She was too old to conceive but said her daughters were willing to produce a fetus to help their father.

On the frontiers of medical technology, the fetus has become the prime source for fresh, living cells to treat certain neurological disorders, including nerve regeneration, diabetes, bone marrow diseases and even some skin disorders. Even though widespread use of these techniques is years away, the debate over using fetal cells to treat disease has already begun.

While few people oppose saving lives with transplants from cadavers, the concept of fetal cell therapy raises difficult ethical questions.

The three women who wanted to conceive in order to harvest fetal cells to treat themselves or family members were unsuccessful in getting U.S. physicians to cooperate. At the same time, their cases illustrate the pressures that are likely to increase on the medical profession to use this potentially life-saving therapy.

A central question in the fetal-cell debate is ownership. Who can grant permission to use fetal cells for some therapeutic purpose? In the world of organ transplants, the dying individual or the next of kin, who are presumed to have the dying individual's best interest in mind, give permission to donate the organs.

"In the world of abortion -- where we get fetal tissue -- the presumption that the mom who had the abortion has the best interest of the fetus in mind is at least challengable," said Arthur Caplan, director of the Center for Biomedical Ethics at the University of Minnesota in Minneapolis.

The circumstances under which fetal cells are obtained intensify ethical concerns.

Earlier this month, Mexico City researchers reported transplanting the brain cells from a spontaneously aborted, or miscarried, fetus into two patients with Parkinson's disease. No one has raised ethical objections about obtaining fetal cells from spontaneous abortions. But logistical problems will prevent their widespread use.

For fetal tissue to be widely used, the main source is expected to be electively terminated pregnancies where the woman would have had an abortion regardless of how the remains may be used.

Abortion foes condemn the use of fetal cells from elective abortions because they fear it might legitimize, or even encourage, abortion because of the potential benefits derived from producing fetal cells.

Others argue that the issues involved with fetal-cell therapy should not be confused with the ethical debate over abortion itself. "The morality of abortion is separate from the question of what to do with the fetal remains after the abortion," Caplan said.

The most troubling issue centers on the fetus that is conceived intentionally to provide tissues to treat an ill individual, especially for a relative of the woman who becomes pregnant.

"It is one thing to take advantage of a tragedy, a suicide, a murder or elective abortion," Caplan said. "It is quite a different thing to create a death in order to find tissue, or organs. You would cross lines if you allowed people to create lives just to end them. That is a line we should not cross."

Even more ominous, say some experts, is the prospect that poor women, especially in Third World countries, could be exploited, becoming pregnant in order to abort and sell the fetal remains.

In the United States, selling organs is illegal, but selling tissues, such as blood, is not.

In December 1986, a number of researchers and ethicists gathered at Case Western Reserve University School of Medicine in Cleveland to propose guidelines for the ethical use of fetal-cell therapy.

Dr. LeRoy Walters, director of the Center for Bioethics at the Kennedy Institute of Ethics at Georgetown University, laid out some of the conclusions: There should be a clear separation between the decisions related to the abortion and the decision to transplant the tissue into another person. The permission of the mother is legally required and sufficient, but the procedure should also be approved by some independent body. Direct donations should not be allowed. The woman having the abortion should not be related to the recipient.

While these issues are unlikely to be faced by many patients, it only is a matter of time, researchers say, as the techniques prove more and more successful.

In addition to the recent Mexican experiments with Parkinson's, researchers at the University of Colorado Health Science Center in Denver have experimentally transplanted fetal islet cells into 20 diabetics, with promising results. If fetal cells live up to their early promise, debate over their use is bound to intensify.

Another technique often discussed is transplanting the blood-forming tissue in the fetal liver as a substitute for bone marrow transplantations. Dr. Robert P. Gale of the University of California at Los Angeles attempted such transplants during the Chernobyl nuclear accident, but those patients died. Dr. Richard O'Reilly, head of the bone marrow transplant program at Memorial Sloan Kettering Cancer Center in New York, said most groups have abandoned using fetal livers for bone marrow transplants because it does not seem to work.