• Journal of fish pathology
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• v.20 no.1
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• pp.83-91
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• 2007

In order to differentiate the gastric tubular dilatation of olive flounder, Paralichthys olivaceus, from an atrophic change, a series of histological studies was carried out for normal gastric gland, naturally occurring and histamine-induced dilated glandular tubules. Normal glandular tubules were histologically quite similar to those already reported from other fish species. Naturally occurring, dilated gastric glandular tubules had the epithelial characteristics suffering from atrophy under light microscope, which was also the case in the histamine-induced gastric gland. But on semi-thin sections the area corresponding to the empty space of dilated lumina were actually shadowed with relatively bright area. Under transmission electron microscope this brightly shadowed area turned out to be an area tightly packed with abundant, slender cytoplasmic processes in both cases. These results strongly suggested that the dilative gastric glandular tubules under light microscope might be a morphological change indicating increased glandular activity rather than a pathologic atrophic change.