Hydropic vacuolation in the liver of three species of fish from the U.S. West Coast: lesion description and risk assessment associated with contaminant exposure.

Hydropic vacuolation (HydVac) of biliary epithelial cells and hepatocytes is described for 3 species of U.S. West Coast bottom fishes. Risk assessment analyses are also conducted to determine if the prevalence of this lesion increases in association with contaminant exposure and site of capture. The morphology of HydVac in starry flounder Platichthys stellatus, white croaker Genyonemus lineatus and rock sole Lepidopsetta bilineata was similar to that described in winter flounder Pleuronectes americanus from the U.S. Atlantic Coast, especially in that HydVac most commonly affected biliary epithelial cells. Hydropic vacuolation was the most prevalent liver lesion in starry flounder and white croaker captured from contaminated environments. Risk assessment analyses confirmed that the relative risk for HydVac increased with the presence of aromatic and chlorinated hydrocarbons in sediment, fish bile, and fish liver for these species. Hydropic vacuolation also frequently occurred in rock sole, but the lesion showed no clear association with contaminant exposure in this species. The types of liver lesions that were useful biomarkers of contaminant effects in fish depended on the species and this factor must be taken into account when evaluating histopathological biomarkers of response to contaminant exposure.

Relationships between toxicopathic hepatic lesions and exposure to chemical contaminants in English sole (Pleuronectes vetulus), starry flounder (Platichthys stellatus), and white croaker (Genyonemus lineatus) from selected marine sites on the Pacific Coast, USA.

Relationships between hepatic lesions and chemical contaminant concentrations in sediments, stomach contents, liver tissue, and bile were statistically evaluated in three species of bottomfish, English sole (Pleuronectes vetulus), starry flounder (Platichthys stellatus), and white croaker (Genyonemus lineatus), captured from 27 urban and nonurban sites on the Pacific Coast from Alaska to southern California. Lesions detected were neoplasms, preneoplastic foci of cellular alteration, nonneoplastic proliferative lesions, unique or specific degenerative/necrotic lesions, nonspecific degenerative/necrotic lesions, and hydropic vacuolation of biliary epithelial cells and hepatocytes. In general, lesion prevalences were significantly higher in all three species captured at chemically contaminated urban sites, and certain lesions had significantly higher relative risks of occurrence at urban sites in Puget Sound, San Francisco Bay, the vicinity of Los Angeles, and San Diego Bay. Concentrations of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, DDT and its derivatives, and chlordanes and dieldrin in sediment, stomach contents, liver, and fluorescent aromatic compounds in bile were significant risk factors for the occurrence of neoplastic, preneoplastic, nonneoplastic proliferative, and specific degenerative/necrotic lesions, as well as hydropic vacuolation. Fish age also had a significant influence on occurrence of several hepatic lesions, but gender was rarely a significant risk factor. These relationships provide strong evidence for the involvement of environmental contaminants in the etiology of hepatic lesions in several marine bottomfish species and clearly indicate the utility of these lesions as biomarkers of contaminant-induced effects in wild fish.

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

The ultrastructure and histology of cholangiocellular carcinomas from feral English sole (Parophyrs vetulus) living in polluted waterways of Puget Sound, WA. are described. Electron microscopy confirmed that biliary epithelial cells were the main proliferative cell type composing this variety of neoplasm. The arrangement of these cells varied from well-organized multiple bile duct-like structures to disorganized multilayered sheets of poorly differentiated biliary epithelial cells. A fibrous stroma consisting of multiple layers of collagen fibers and fibroblasts, with macrophages and various blood cell types scattered among these layers occurred between bile duct-like structures or aggregates of biliary epithelial cells. Hepatocytes were not apparent in these neoplasms except within small necrotic regions surrounded by neoplastic biliary epithelial cells. No virus-like particles were observed among the cases examined in this study.

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.

Changes in the surface epithelium of the developing olfactory organ in the sand sole (Psettichthys melanastictus) and the rex sole (Glyptocephalus zachirus).

The olfactory organ of the sand sole (Psettichthys melanastictus) and the rex sole (Glyptocephalus zachirus) begins its development as a primary olfactory groove containing a sensory epithelium with two or more cell types. The groove becomes dumbbell shaped as its lateral margins grow towards each other and eventually fuse, resulting in the formation of an olfactory chamber with openings for the anterior and posterior nares. Dimensions of the primary olfactory groove are different between these two species. Fusion of the olfactory bridge occurs about the time of metamorphosis in the sand sole, but before metamorphosis in the rex sole. The sensory epithelium of the sand sole larva contains microvillar cells, ciliated type I cells, and ciliated type II cells at hatching, while the rex sole larva has only microvillar and ciliated type II cells. Ciliated type I cells were observed in rex sole only after the olfactory bridge had fused. The olfactory epithelium in both species is directly exposed to the fish's environment for some length of time before it becomes enclosed within an olfactory chamber.

The comparative ultrastructure of the egg membrane and associated pore structures in the starry flounder, Platichthys stellatus (Pallas), and pink salmon, Oncorhynchus gorbuscha (Walbaum).

Eggs of the starry flounder (Platichthys stellatus) and pink salmon (Oncorhynchus gorbuscha) were examined by scanning and transmission electron microscopy to determine differences in egg membrane structure with reference to contrasting ecological conditions in which the eggs normally develop. The egg membrane of the starry flounder constitutes 0.22--0.50% of the egg's diameter. The zona radiata is composed of 6 continuous horizontal lamellae, covered by a thin triple layered border, and pierced by numerous regularly spaced pore canals. The micropyle canal measures 8 microns at the opening and tapers to 3.6 microns as it penetrates the membrane. In contrast, the thicker membrane of the pink salmon egg forms 0.80--1.0% of the egg's diameter, is composed of numerous short discontinuous lamellae which are pierced by pore canals, and is covered by a coating of irregular thickness. The 15--16 micron micropyle opening is surrounded by an area of protrusions, and the funnel-shaped canal tapers to 2 microns at its terminal aperture. Contrasting environmental conditions during embryogenesis of these two species may be reflected by the thin membrane and simple lamellar structure in the pelagic egg of the starry flounder, and the thick membrane and complex lamellar structure in the demersal egg of the pink salmon.