Donating them to medical research, meaning stem-cell research, wasn't an option before 1998 when professor James Thomson, a biologist at the University of Wisconsin, first culled a stem-cell line from a human embryo.
And this is what started the whole controversy, Thomson acknowledges.
"That's the first cell line, yeah," he says, as he looks through a microscope.
The reason embryonic stem cells are so prized is because they have the unique ability to grow into all different kinds of cells in the body, like kidney cells, brain cells and even heart cells.
He showed 60 Minutes stem cells that had been transformed into human heart cells.
"You can see that they actually function like individual heart muscles. They actually contract," Thomson explains. "These would be like a millimeter across."
And the cells beat.
The hope is that, one day, healthy stems cells like these will replace diseased cells in the body. But Thomson says to move the science forward, researchers need more embryos.
"It's gonna help people, and we don't have a good crystal ball exactly how," he says. "But there's very rarely this amount of enthusiasm in science for something."
Thomson says he's at the moment where he needs to have new cell lines. "It's right — at the moment where we need to see things accelerated. We've really gone fairly slowly for something this important," he says.
What is holding things up is President Bush's policy: he has banned the use of federal money for work on any embryonic stem cells created after August 2001. Extracting stem cells destroys embryos, which he opposes — a point he highlighted in his 2006 State of the Union speech.
"Human life is a gift from our Creator and that gift should never be discarded, devalued or put up for sale," the president said.
The president, who promotes something known as the "adoption option," met last year with a group of parents and their children who owe their lives to couples who bequeathed them their leftover frozen embryos.
Millions of federal dollars now go to programs that promote the "adoption option," like the National Embryo Donation Center in Knoxville, Tenn.
Deliveries here are not made by the stork, but by FedEx. Batches of frozen embryos are flown in from couples across the country. But the number of so-called adoptions through programs like this one totals only about 100.
"We need to do a better job of encouraging people to adopt," says Robert George, a professor at Princeton University and a member of President Bush's Council on Bioethics.
George concedes there are many more frozen embryos than will ever be donated to other couples.
"If we cannot encourage more parents to permit the embryos to be adopted, we're going to be stuck," he says. "And the reality will be that those embryos remain in cryo-preservation indefinitely."
But leaving embryos frozen in perpetuity, he says, is morally preferable to destroying them for stem cell research. To Art Caplan, a bioethicist at the University of Pennsylvania, that makes no sense.
"You got people in wheelchairs. You got people trying to understand how to cure cancer," Caplan says. "You know, people who want to understand genetic diseases and you have embryos frozen that no one will ever use for any purpose whatsoever. There's a moral equation here, too. And it seems to be to lead toward research, not just perpetual freezing."
He recently did a survey of the nation's fertility clinics and found that excess embryos are not only frozen, but many — thousands a year — are routinely destroyed with the patients' consent.
"Some patients ultimately will finish their family, have, maybe they have a couple of embryos in storage. They do decide to discard those. That's their decision," Scott says.
Asked how they are discarded, Scott says: "We simply remove them from the liquid nitrogen. They thaw. And then we discard them in bio-hazard waste. They're cells; they would be discarded the way any other cell that was removed from the body would be discarded."