From the article: “A human embryo implants in the womb around seven days after fertilization if everything goes correctly. Due to technological and ethical constraints, the embryo becomes unavailable for study at that point. That is why scientists have already created stem cell models for various kinds of embryonic and extraembryonic cells in order to investigate human development in a dish.”

The new cell is actually a stem cell that resembles the stage of development they currently don’t have access to.