Fig. 2. Zebrafish adult liver. (A,B) Histological sections from an adult male liver. In A, two intrahepatic veins are visible (arrows). Identification of either vein as a portal or hepatic venous radicle is not possible. Sinusoidal channels containing nucleated red blood cells are visible between hepatocytes, most prominently in B (white arrowheads). Contiguous sinusoids linking adjacent venous structures are not seen. Large bile ducts are also visible in cross section (arrows in B), as is a smaller biliary radicle (arrowhead). Such ducts are infrequently seen in the liver periphery. (C,D) Confocal projections of adult liver samples processed for immunohistochemistry (IHC) using anti-human cytokeratin 18 (C) and anti-human P-glycoprotein (D) antibodies. Note branching anastomotic network of bile ducts, and tubular canaliculi described in other teleosts. (E,F) Transmission electron micrographs of adult liver. In each, ductular cells anastomose with hepatocyte canaliculi that have prominent microvilli. Multiple canaliculi converging on a single bile duct are evident (F). bd, bile duct; c, canaliculus; dc, ductular cell; h, hepatocyte.