The Royal College of Obstetricians and Gynaecologists suggested that embryos should not be allowed to develop in vitro beyond a limit of seventeen days, as this is the point at which early neural development begins. The British Medical Association favoured a limit of fourteen days and a number of groups, including the Medical Research Council and the Royal College of Physicians suggested that the limit should be at the end of the implantation stage. Again, some groups submitting evidence suggested that no embryo which had gone beyond the beginning of the implantation stage should be used for research.