The tiny fists. The sleepy, swollen eyes. The infant floating dreamily in an amniotic sea.
Is this where human embryonic stem cells come from?
No. Not at all.
But some who are fighting any expansion of stem cell research evoke just that image.
"They are chopping up babies in order to get stem cells," said Patrick Lee, a philosophy professor at Franciscan University in Steubenville. "They are babies. Not everyone calls them babies, but they're tiny human beings."
This is the ethical heart of every debate over the treatment of human embryos, whether it's about their dissection to create stem cells, their destruction in fertility clinics, or their manufacture in a laboratory from an egg that's been tricked: Is this diminutive soccer-ball of cells, smaller than a pinhead, without limbs, or nerves, or even blood vessels, a human being?
For those who believe it is, the embryo in a petri dish -- intended solely for research, never to become a child -- is the moral equivalent of the embryo nestled in the uterine lining -- a child. The fact that an embryo may become a human, given the chance, makes it sacred, they say.
But others disagree with granting that status to an embryo.
An early embryo is "a possible person, a potential person, but not a person," says Arthur Caplan, a professor of bioethics at the University of Pennsylvania in Philadelphia. "It isn't anything equivalent to a person until it's implanted in a human body. It's not coherent at all to confuse acorns with trees, or computer programs with computers.
"It's like a program: It's not a baby, but a set of instructions to make a baby."
Not surprisingly, people who wish to protect embryos don't see it that way.
An embryo's potential dictates its status, Mr. Lee said. An embryo has "the full program and the active disposition to develop itself to maturation," he said. "It's growing in its own direction and is already a human being, albeit at an immature stage."
"I don't think the science is correct," Mr. Caplan counters. Stem-cell opponents "think embryos are babies, that everything you need is in the embryo. That's not true," he said.
Although an embryo has a genetic program, "it needs to interact with more information from the mother" before it can develop into a human.
Bonnie Steinbock, a bioethics professor at the State University of New York at Albany, couched the issue this way: "If you had a fire break out in an infertility clinic, and you had a choice between saving 10 or 100 or 1,000 frozen embryos, and one 2-year-old child, or a 6-month-old baby, would you hesitate for a second?"
Embryos "do not have the same moral status as you and me," she said. "A baby is conscious and aware and can feel things."
Only a small percentage of embryos conceived naturally survive to form a child, studies show. Estimates suggest that between 60 and 80 percent fail to even implant in the uterus, and another 10 to 30 percent die shortly after implantation.
In U.S. fertility clinics, more than 65 percent of all attempts to put embryos in the womb fail, and those attempts may include two, three, four, or more embryos.
"The majority of embryos can't become anything," Mr. Caplan said. No one really knows why they fail. Stem-cell opponents say they probably are not truly embryos, but examples of incomplete fertilization. Others point to studies of embryos that show as many as half of them carry chromosomal damage.
Those who consider embryos "human" say that embryonic deaths do not lessen their value.
"We don't kill human beings at any other stages just because their natural mortality rate is high," said Richard Doerflinger, deputy director of pro-life activities for the U.S. Conference of Catholic Bishops.
Mr. Lee said: "If in some areas, we have infant mortality rates of 40 to 50 percent, that doesn't prove those are not human beings. I think, if we were talking about infants, or retarded children, who we knew were going to die in the next week or two, we still would not argue, 'look, we still can make use of their body parts.' "
For those who favor embryonic stem cell research, the moral issue lies elsewhere: Is it right to discard embryos made in fertility clinics when those embryos may help other people?
In fact, stem cell research may move forward faster because of the growing list of advocates: the thousands of patients and parents of sick children looking for a cure, Ms. Steinbock said.
Stem-cell opponents also are concerned about the prospect of cloning to create stem cells. In cloning, the egg nucleus is removed and replaced by the nucleus of an adult cell, such as a skin cell. The reconstituted egg then is tricked by a chemical change or a jolt of electricity into behaving like an embryo. When it grows to about 100 to 150 cells, the cloned embryo is dissected, and the stem cells are collected and grown in laboratory dishes.
There is broad agreement that cloning to produce a pregnancy is a bad idea. But some believe the creation of cloned embryos to make stem cells is essential.
Stem cells made this way will be the exact genetic match of the person whose skin cell or other adult cell went into the clone.
Such stem cells could be transferred back to the skin cell donor, theoretically, without fear of immune rejection.
But this opens up the morally troubling possibility that embryos are being made in order to destroy them, stem cell opponents say.
"When they get stem cells that way, they're deliberately destroying the embryonic human being, for the sake of using his body parts for someone else," Mr. Lee said.
The harvest of embryonic stem cells turns human life into a commodity, said Wesley J. Smith, a lawyer and senior fellow at the conservative Seattle think tank, the Discovery Institute.
He called the idea of cloning for stem cells "wildly impractical. Where are you going to get millions and millions of human eggs required to treat every patient?"
He imagines a scenario where women in poor countries are used as egg sources. "It could lead to exploitation of women, poor women in particular, and reduce them to a commodity."
Egg donation for cloning makes even some stem-cell supporters uncomfortable.
"Somehow some woman is going to have to donate so many [eggs]," said K. Sue O'Shea, a University of Michigan researcher working with human stem cells.
The hormone injections necessary to create eggs for donation can be at the very least uncomfortable, and in rare cases, life-threatening. And it's not as though every egg will easily make a cloned embryo. Human embryo cloning to make a stem cells has, in fact, worked only once so far. That effort used 242 eggs to make one stem cell line.
Many hope that researchers will learn enough about how an egg reprograms an adult cell to make egg-free stem cells someday. But in the meantime, because cloning research can continue unfettered in private industry, many say strict regulations covering egg donations are needed.
As it stands, egg donation in the fertility industry faces little regulation.
"A policy should be developed that achieves broad moral principals," said Daniel Perry, the president of the Coalition for the Advancement of Research, an umbrella organization lobbying for stem cell research. "Human beings and body parts and the reproductive material should not become instruments of commerce."