TELEOST FISH GRANULOMAS - SOME EPITHELIAL-CELL CHARACTERISTICS IN THEIR EPITHELIOID CELLS

On examination of transverse sections of paraffin embedded specimens f rom 127 fish from four genera, 16 fish were found to have granulomas i n various visceral organs (Kidney, liver, peritoneal fat and spleen). The number of granulomas varied from one to 14 per fish organ. The cen tral necrotic mass of the granuloma was positive for keratin, but the epithelioid cells were negative for cytokeratin using monoclonal antib ody to human keratin. Acid fast bacteria (mycobacteria) were demonstra ted in the sections of the discus (Symphysodon sp.) and neon tetra (Hy phessorbrycon innesi) fishes, but not those of grass carps (Ctenophary ngodon idella) and crucian carps (Carassius carrassius). Neither fungi , other types of bacteria, nor other agents could be demonstrated in a ny fish. Electron microscopic studies revealed epithelial features in epithelioid cells. These were numerous interdigitations, network of to nofilaments and several desmosomes.