Box 1. Sections of current International Society for Stem Cell Research guidelines relevant to human embryoids [23]

Forms of research that are permissible only after review by an EMRO process Research involving the in vitro culture of embryos or experimental generation of embryo-like structures that might manifest human organismal potential, to ensure minimal periods of in vitro culture, as justified by compelling scientific rationale. Prohibited research activities 1. In vitro culture of any intact human pre-implantation embryo or organized embryo-like cellular structure with human organismal potential, regardless of derivation method, beyond 14 days or formation of the primitive streak, whichever occurs first. 2. Experiments whereby human embryos or organized cellular structures that might manifest human organismal potential are gestated ex utero or in any non-human animal uterus.