part of part of has part has part surrounds surrounds existence starts during existence ends during Mammalia embryo stage portal vein bile duct bile duct epithelium late embryonic stage multicellular anatomical structure ductal plate Temporal stages still need to be fully researched across species. In human, ductal plate is a double-layered cylindrical structure of bile duct epithelium that surrounds the portal ramifications by the eighth gestational week. After approximately the 12th gestational week, remodelling of ductal plate begins, and maturity is attained by the end of gestation or early postnatal period. UBERON:8410003 Paola Roncaglia