Lifeboat Foundation

They were right. Last week, writing in Science, a Japanese team reported a formula that transforms human blood cells into immature eggs. With the help of an artificial womb made from mouse ovary cells, the human cells underwent changes to their DNA that mimics those in a 10-week-old, normal human egg.

The resulting eggs are far from full-blown eggs, and they can’t yet be fertilized to create human embryos.

But “this cannot be denied as a spectacular next step,” said Dr. Eli Adashi at Brown University, who was not involved in the study. “Considering how difficult this has been in a human, [this new study] in a way broke the ice.”