Embryonic Remnants and Pathology
Embryonic remnants are often found as incidental findings on routine microscopy. They are derived from the vitelline (omphalomesenteric) duct (the embryonic structure which connects the midgut lumen within the yolk sac to the developing fetus) and the allantois (the primitive extraembryonic urinary bladder). In most cases they are asymptomatic, but the vitelline duct may be associated with intestinal atresia and Meckel’s diverticulum, whilst pyelonephritis and abscess formation may complicate a persistent urachus (allantoic duct). Both types of remnant may present as cystic lesions of the cord. This chapter describes the embryology of such lesions, outlines the diagnostic features of each and briefly describes associated disorders.
KeywordsUmbilical cord Vitelline duct remnant Vitellointestinal duct Omphalomesenteric duct Allantoic duct Urachal duct Urachal remnant
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