by Philip Ball
Originally published December 12, 2016
Here is an excerpt:
That limit has remained in place ever since. But now some scientists believe it should be extended to 28 days. These proposals were discussed on 7th December at a meeting in London organised by charity the Progress Educational Trust. It marked the beginning of what seems likely to be a broad and extended discussion among scientists, bioethicists, fertility specialists, religious leaders and others who have a stake in the moral, legal and scientific status of the human embryo.
So the 14-day embryo has begun the process that leads to the laying down of the human body plan—but only just. A key stage, called gastrulation, begins around day 16: this is when the embryo acquires a three-layered structure, the precursor to the appearance of different body-tissue types. So the time between day 14 and day 28 sees the embryo progress through some crucial stages of development, and understanding the details of what goes on, such as the genetic changes involved, should provide a wealth of information that might offer insights into human health, disease and malformation. Much of what we know about these stages at present comes from studies of mice—but as several of the speakers acknowledged, there are some important differences between mice and men.
This is why it looks so enticing for cell biologists and geneticists to investigate the post-14-day embryo. But should that be allowed by a change in the law?
The article is here.