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By means of a special apparatus a superficial lesion was made in the common bile duct of the rabbit; the healing of the lesion was studied by transmitted light microscopy and scanning electron microscopy. Within a few hours the cells in the epithelial margin became flattened and started to migrate over the bottom of the defect. In most cases the lesion was closed after 16 to 24 hours by epithelial migration. After 24 hours a sharp increase in the mitotic activity occurred, first especially in the crypts, later also in the superficial epithelium. A blood clot on or necrosis of the wound basis seemed to stop the migration of the epithelium. Necrosis of the connective tissue in the central part of the lesion occurred after 24 hours if the lesion was not epithelialized, possibly by the action of bile. In that case the lesion healed by secondary intention. After 2-8 weeks all lesions were healed completely, no strictures being observed.