Ultrastructural findings of intracytoplasmic eosinophilic globules in hepatocytes of stranded cetaceans

Abstract

This work describes the ultrastructure features of intracytoplasmic eosinophilic globules founded in hepatocytes of seven stranded cetaceans. Previous ultrastructural studies of these findings were performed by other authors, being described as diffusely moderately electrodense inclusions with an occasionally central or eccentrical core of highly electron-dense material. Kennedy et al. suggested that those structures could be of lysosomal origin containing serum proteins and other materials within intracytoplasmic vacuoles. To carry out this work we selected livers of seven animals stranded in Canary Islands (two Delphinus delphis, one Stenella coerulealba, three Stenella frontalis and one Tursiops truncatus) which showed immunohistochemically positive globules to fibrinogen and/or alpha-1-antitrypsine. Six of these animals stranded alive and one was found dead but with signs of a possible alive stranding. Those liver samples were processed routinely for electron-microscopy. Results indicated that fibrinogen positive inclusions presented different morphological shapes, without a visible membrane and a moderate uniform electron density. In some of those inclusions a core with higher electron-dense material and radial finger like structures were also detected. Alpha-1-antitrypsine positive globules presented a more granular appearance and a visible membrane. In some of the hepatocytes a central core was also observed. Preliminary conclusions indicate that a central core could be found in globules immunohistochemically stained with both fibrinogen and/or alfa-1-antitrypsine. These results contribute to a better knowledge of these characteristic morphological changes found frequently in whales and dolphins stranded alive as well as in by-catch dolphins, reported previously by our group.