Purpose or Case Report: Embryogenesis is a complicated process that requires fine-tuning of multiple factors. Certain transient vestigial structures play a key role in the development and maturation of the developing organs. Persistence or incomplete regression of these primitive structures can give rise to numerous disease entities that may vary from incidental findings to potentially life-threatening conditions. Knowledge of these embryonic remnants is critical for radiologists, as they are encountered in daily practice and can often mimic other pathologies. The purpose of this educational material is to provide a comprehensive presentation of the most important embryonic remnants that radiologists and trainees need to be aware of. The structures that will be discussed, along with their related pathologies, include: aortic arches, cardinal veins, branchial arches, thyroglossal duct, thymopharyngeal duct, nasopalatine duct, Rathke’s cleft, allantois, vitelline duct, Mullerian duct, Wolfian duct, cloaca, notochord, neurenteric canal, falcine sinus, septum pellucidum and primary vitreous. Facts about their embryological background, anatomical location and clinical manifestations will be provided, as well as representative radiological images and differential considerations.
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