Scanning electron microscopy on the rat liver with alpha-naphthylisothiocyanate- induced cholestasis.

Intrahepatic cholestatic rat livers were studied with the scanning electron microscopy at 3, 24, 48 and 96 hours after a single dose administration of alpha-naphthylisothiocyanate (ANIT, 100 mg/kg body weight). Cholestasis reached the peak at 48 hours and decreased thereafter. On intercellular surfaces of hepatocytes, round indentations appeared at 3 hours and became larger and more numerous at 24 hours. On sinusoidal surfaces, small pits were observed at 3 and 24 hours. Bile canaliculi were dilated and their microvilli became shorter and sparse in all specimens. They became tortuous at 3 hours and after 48 hours tortuous canaliculi were greatly increased. Side branches of the bile canaliculi showed increase at 24 hours and were numerous at 48 hours. At the same time when changes in bile canaliculi were most remarkable, some of side branches communicated directly with the Disse space. At 96 hours canalicular changes became less observable and the communications disappeared. In conclusion, in the liver with ANIT-induced cholestasis, bile components possibly regurgitate 1) from the hepatocytes by reversed pinocytosis through intercellular surface indentations and sinusoidal surface pits in the early phase of cholestasis, and 2) from the bile canaliculus through the bile canaliculus-the Disse space communications at the peak of cholestasis.