Question
Further to the Written Answer by Lord Darzi of Denham on 21 April (WA 234) regarding differences between retention of the structure of an inner cell mass on different surfaces, whether seeding a human blastocyst onto feeder cells more closely resembles a collagen surface or naked plastic.
Answer
The Human Fertilisation and Embryology Authority (HFEA) has procedures in place to ensure that centres comply with Sections 3(3)(a) and 3(4) of the 1990 Human Fertilisation and Embryology Act 1990. The HFEA checks compliance on a case by case basis upon inspection. The culture of mouse embryos, as described by Hsu et al (1974), involved culture on a collagen surface with the intention of nurturing a 3D structure. As far as the HFEA is aware, this study is the only one in which contractions resembling a heart beat have been observed in mammalian embryos cultured in vitro. The gestation period of a mouse is 19 days, meaning at 10 to 14 days a mouse embryo would be over halfway through the normal gestation period. When culturing inner cell masses which have outgrown from the structure of an embryo, centres must ensure that the method used does not allow embryos to develop past 14 days or the appearance of the primitive streak. The method used must result in a flat culture of cells and not a 3D structure. Embryos that have attached and outgrown on the surface of the dish no longer have the organisation structure of a viable embryo.