The ultrastructure and histology of hepatocellular carcinomas of English sole (Parophrys vetulus) from Puget Sound, Washington.

The cellular and subcellular morphology of hepatocellular carcinomas (HCs) from feral English sole (Parophrys vetulus) living in contaminated waterways of Puget Sound was compared with normal-appearing liver from English sole inhabiting reference sites in Puget Sound. The most distinctive feature of English sole HCs was the occurrence of large dilations of RER containing densely packed microfilamentous-like material that was often arranged in complex branching arrays that nearly filled the cytoplasm of affected hepatocytes. These arrays have not previously been reported in HCs of any other fishes. Several other characteristics also distinguished HCs from reference liver, including: the apparent proliferation of Golgi complexes and mitochondria; occurrence of torus-shaped mitochondria; elongation and/or proliferation of perisinusoidal cells; and inclusion of large intraheptocellular vacuoles.