embryo" in the title of the second study was later changed to the alternative term "embryo model".

On 6 September 2023, Nature published research that the Weizmann Institute team created the first complete human day 14 post-implantation embryo models, using naïve ES cells expanded in special naive conditions developed by the same team in 2021. It also uses reprogrammed genetically unmodified naïve stem cells to become any type of body tissue. Chemicals were used to coax these stem cells