Morphometry of Hepatic Neoplasms and Altered Foci in the Mummichog, Fundulus heteroclitus

Abstract

The goal of this study was to intensively sample a small number of livers from a population of mummichog exposed to PAH-contaminated sediments and evaluate them for lesion pathology, distribution, shape, and volume, and the number of histological sections needed to adequately describe the extent of various lesions. Volumetric data for each lesion type from each step section was derived from digitized section images. The total number of hepatic alterations ranged from 10—125 per fish. Alterations included: eosinophilic, basophilic, and clear cell foci; hepatocellular carcinomas; hemangiopericytomas; and cholangiomas. Lesion volumes ranged from 0.00012—64 mm3 and represented 0.21%—67% of total liver volume. There was a tendency for the lesions to be more dorsal-ventrally compressed than spherical or ropelike when observed from longitudinal sections. Periodic subsampling of the data indicated that, on average, 6 evenly spaced, longitudinal histological sections were required to accurately estimate lesion volume and extent in our model population. These data provide a formulation for histological sampling techniques and methodological support for piscine and other cancer study models that observe lesion volume changes over time. Further, this study fosters the development of early quantitative endpoints, rather than using a large number of animals and waiting for tumor progression or death to occur.