extraembryonic structure UBERON:0000478 https://orcid.org/0000-0003-2569-1939 | https://orcid.org/0000-0002-7535-4583 A multicellular anatomical structure that is associated with an embryo and derived from the zygote from which it develops, but which does not contribute to the embryo proper or to structures that are part of the same organism after embryogenesis. Planarian_Anatomy developing anatomical structure