Self-organization of the human embryo in the absence of maternal tissues

This study led by Magdalena Zernicka-Goetz at the University of Cambridge reports the development of an “in vitro system to culture human embryos through implantation stages” (2016:700) in the absence of maternal tissues, which were previously thought to be required to mimic the implantation of an embryo in an uterus. The scientists adapted a protocol for mouse embryo culture, using an extracellular matrix. Implantation is a milestone in human development, thought to induce remodeling of the embryo and gastrulation. By allowing study of the human embryo beyond approximately the first week of development, this system and study shed light on the self-organizing properties of the human embryo. While this system would make human embryo culture beyond the two-week mark possible, the authors uphold the 14-day rule as an ethical barrier, writing, “for ethical reasons we are obliged to stop our cultures at day 14 of development or before the primitive streak formation” (2016:706).