Question
To ask Her Majesty's Government further to the Written Answers by Lord Darzi of Denham on 12 January (WA 96-97) and 10 February (WA 176), how the Human Fertilisation and Embryology Authority classifies an outgrowing embryo in terms of ability to develop a primitive streak if the authority does not consider published data regarding thereported ability of primate embryonic stem cells to exhibit behaviour consistent with early primitive streak formation when grown at high densities; and how the density of cells within an outgrowing embryo compares to a conventional culture of embryonic stem cells.
Answer
Subsection 1(1)(a) of the Human Fertilisation and Embryology Act 1990 defines an embryo as a live human embryo where fertilisation is complete. As I stated in my Answer of 10 February 2009 (col. WA 176), the embryonic masses that form when embryos outgrow their structure are not considered by the Human Fertilisation and Embryology Authority (HFEA) to be embryos because they do not have the 3D organisation of an embryo, do not have a relationship between extra-embryonic and embryonic tissue essential for normal development and do not develop a primitive streak. However, the HFEA regulates the creation and use of embryonic masses as part of its routine work of examining the creation, use and storage of all human embryos at licensed centres. The HFEA has advised me that its Scientific and Clinical Advances Advisory Committee (formerly knows as the Scientific and Clinical Advances Group) is of the view that the embryonic masses that form when embryos outgrow their structure would not develop a primitive streak but it is possible that primitive streak-like cells may be detected. I have no further comments on the remarks of the Head of the Institute of Human Genetics at Newcastle University.