part of develops from develops into corpus allatum primordium FBbt:00001716 embryonic corpus allatum fly_anatomy.ontology The primordium that will form the embryonic/larval corpus allatum, a substructure of the embryonic/larval ring gland. It is a paired structure that becomes distinct in early dorsal closure between the head mesoderm and the epidermis of the gnathal segments. During dorsal closure the paired primordia move dorsally to meet and fuse above the cardioblasts of the developing aorta. embryonic/larval corpus allatum dorsal closure embryo cardiogenic mesoderm ring gland primordium trunk mesoderm derivative