asked Her Majesty's Government:
Further to the Written Answer by Lord Darzi of Denham on 22 January (WA 28) regarding the culture of embryos for more than 14 days in vitro, how it has been proven that the zona pellicida is absolutely required for embryonic development; and whether peer-reviewed literature supports the view that no embryo allowed to outgrow after attaching to the surface of a culture dish would ever develop in a mammal, and therefore would not be classed as an embryo by the Human Fertilisation and Embryology Authority. [HL2353]
The Human Fertilisation and Embryology Authority's (HFEA) decision, based on the available evidence, is that outgrowing embryos have ceased to be human embryos. This conclusion was reached in part because an outgrown “embryo” no longer has the organisational structure of a viable embryo, including signs representative of primitive streak formation and there is no longer a relationship between the trophectoderm and the inner cell mass. The embryo outgrowth is therefore not considered an embryo by the HFEA as it is potential-less and would not be able to develop if implanted in a woman.