The mouse embryos looked perfectly normal. All their organs were developing as expected, along with their limbs and circulatory and nervous systems. Their tiny hearts were beating at a normal 170 beats per minute.
But these embryos were not growing in a mother mouse. They were developed inside an artificial uterus, the first time such a feat has been accomplished, scientists reported on Wednesday.
The experiments, at the Weizmann Institute of Science in Israel, were meant to help scientists understand how mammals develop and how gene mutations, nutrients and environmental conditions may affect the fetus. But the work may one day raise profound questions about whether other animals, even humans, should or could be cultured outside a living womb.
In a study published in the journal Nature, Dr. Jacob Hanna described removing embryos from the uteruses of mice at five days of gestation and growing them for six more days in artificial wombs.
Two other papers published in Nature on Wednesday report on attempts that edge near creating early human embryos in this way. Of course, Dr. Meissner said, creation of human embryos is years away — if it is permitted at all. And for now, international regulations prohibit studying human embryos beyond 14 days of fertilization.
In the future, Dr. Tesar said, “it is not unreasonable that we might have the capacity to develop a human embryo from fertilization to birth entirely outside the uterus.”
Of course, even the suggestion of this science fiction scenario is bound to horrify many. But it is early days, with no assurance human fetuses could ever develop entirely outside the womb.