Scanning electron microscopy of the bile ductule.

Scanning electron microscopy of a liver biopsy specimen from a patient 6 months after the onset of acute hepatitis revealed a normal appearing bile ductule. The bile ductule was 13 micron in outer diameter and 1.5-2.7 micron in inner diameter. The ductular lumen was surrounded by two ductular cells and ampullary dilated at the canalicular side. In the lumen, intracytoplasmic diverticles were observed with an orifice diameter of 0.9 micron. About 15 microvilli 0.4-0.6 micron in length and 0.1 micron in thickness were observed on 1 micron2 of luminal surface. The number of microvilli was calculated to be approximately 1,500 per ductular cell. A single cilium 0.15 micron in diameter at the base and 0.10 micron at the trunk, and 7-15 micron in length was found on each ductular cell. The cilium arose from a recess at the canalicular side of the ductular cell, and the free-end was on the bile-duct side. The cilia seemed to play an important role in bile flow to the duct. Sometimes between the ductular cells at the edge of the basal portion a cell was intercalated with thin processes. Such thin processes were not observed on ductular cells.