GROWING NUMBER OF FROZEN EMBRYOS RAISES QUESTIONS.

Byline: Gina Kolata The New York Times

Robert Prosser, an embryologist at Columbia-Presbyterian Medical Center in New York, guards the future children of hundreds of couples. He keeps them in a locked room, frozen in tiny straws and immersed in three barrel-like tanks of liquid nitrogen.

The tanks are connected to an elaborate alarm system that telephones Prosser and others if it senses a slight rise in a tank's temperature. A tank of liquid nitrogen, otherwise empty, is always ready in case one of the other storage tanks fails.

No precaution is too great for these embryos, Prosser said. ``We treat them as though they are viable developing babies,'' he said.

Tens of thousands of embryos are steadily accumulating in tanks of liquid nitrogen across the country, an eerie consequence of the recent success of in vitro fertilization. They have not been genetically engineered, and they are not clones. Each is the product of the union of one egg and one sperm. Infertile women now routinely have eggs harvested from their ovaries, fertilized in the laboratory and then implanted into their wombs. Many of them deliver babies. And, just as routinely, many have leftover embryos, which are frozen and stored.

But the ranks of frozen embryos raise a host of legal, emotional and ethical questions. These questions become even more complex when the people who provided the eggs and sperm for the embryos divorce, die or simply lose contact with the centers where their embryos are stored.

At New York Hospital-Cornell Medical Center, Dr. James Griffo, the director of reproductive endocrinology, has thousands of frozen embryos. ``It's a full-time job for someone to keep track of them,'' he said.

A decade ago, a woman was delighted if in vitro fertilization, an arduous regime of hormone injections and surgical procedures, produced even a few embryos that could be transferred into her womb. Now, with the success of freezing, ``people are literally disappointed'' if they do not have leftover embryos that can be stored, said Dr. Mark Sauer, director of Columbia's in vitro fertilization program. Unused embryos can be discarded, but virtually every couple with extras wants them frozen.

The embryos are, in a sense, a sort of perpetual youth for the couples who own them. As a woman ages, her ovaries give out and she can no longer produce eggs that are capable of being fertilized. But a woman with frozen embryos can become pregnant in middle age, or even beyond.

They also offer a kind of immortality. They can be stored indefinitely, and they can be a source of children even after a parent has died. Some women with cancer have stored embryos before undergoing chemotherapy and radiation, which damage the ovaries, causing sterility; unlike sperm, unfertilized eggs cannot be stored by freezing them.

Some of the women with cancer have died, and their relatives are now selecting surrogates to carry the embryos they left behind, bearing children for these women even beyond the grave.

The embryos are cells at the very dawn of human development. Some are just a single cell: a fertilized egg. The largest are balls of eight cells. If fertilization had taken place naturally, an eight-cell embryo would barely have begun its journey down a woman's Fallopian tube to her uterus.

Couples have mixed feelings about these microscopic balls of cells. ``When you ask couples, `How do you feel about its status?' they'll say, `It's not really a baby.' But when you talk about discarding, it becomes a fetus,'' Sauer said.

Dr. Robert Anderson, director of the Southern California Center for Reproductive Medicine in Newport Beach, said one of his patients had buried her embryos rather than have Anderson flush them away.

But no federal agency has responsibility for overseeing decisions about these embryos. So legally, the status of such embryos is uncertain, said Lori Andrews, a professor at the Chicago-Kent College of Law who teaches a law course on reproductive technology.

One state, Louisiana, says a frozen embryo is a person and cannot be discarded; such embryos must be kept in perpetuity. In Illinois, the attorney general said a woman who had a frozen embryo was considered pregnant. But Andrews said, ``In most states, the embryo is in legal limbo.''

Meanwhile, the frozen embryos continue to accumulate nationwide at the rate of 10,000 a year for the past five years, Andrews said.

``You can quickly figure out the magnitude of the problem,'' Sauer said. ``You are the trustee for these embryos. You are charged with keeping them forever.''

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Photo

Photo: Human embryos are kept frozen in tanks like this.

The New York Times