The “world’s leading scientists” gathered at University College London on 7 December 2016 to explore extending the 14-day limit on embryo experimentation from 14 days to 28 days. Presently the consensus of that meeting is not known. The Guardian has published a nice summary of the background and future implications of the issue (link HERE). Jon Holmlund offered his comments in this blog back in May when researchers artificially grew human embryos to 13 days gestation. Since this issue is back in the news, a few additional thoughts are offered below.
Space does not permit a detailed history of the details of the discussion behind the original 14-day rule endorsed by the Warnock Committee in the UK (see HERE for one such extended summary). The original limit was arbitrary but coincided with the development in the embryo of the primitive streak, a precursor to the nervous system, such that experimentation on an embryo before this stage was believed to eliminate the possibility of that embryo experiencing pain. The implementation of the 14-day rule essentially permitted experimentation to proceed resulting in the successful development of IVF.
Regardless of the ethics, the 14-day rule has been a hard barrier scientifically until just recently. Just because we can breach the 14-day barrier, why go beyond? Allowing experimentation on the embryo out to 28 days would allow scientists to learn about the process of gastrulation, the process that lays down the body plan and where the three tissue layers (ectoderm, mesoderm and endoderm) begin to subspecialize. If we have ethically permitted experimentation on embryos up to 14 days gestation, shouldn’t we just nudge it out a little further?
To quote Jon Holmlund: “In the name of God, forbear!” Interestingly, for different reasons, Mary Warnock agrees with him. Per the Guardian article, she worries:” If we raise the limit, objectors could argue that the 14-day rule has remained intact simply because no researcher had the technique to keep an embryo alive for so long, and that now one has been discovered the rush down the slippery slope will follow. They will say: ‘We always knew that the slippery slope would prove itself.’”
Experimentation on a human embryo at 14 days of gestation is still experimentation on a human being made in the image of God. Perhaps the upcoming debate on extending the 14-day rule will actually result in Warnock’s fear, that we agree that the original 14-day limit was indeed too long to be slipping and sliding?