Histopathological Findings of Cultured Tiger Puffer Takifugu rubripes Naturally Infected with “Kuchijiro-sho”

(Studies on “Kuchijiro-sho” of Cultured Tiger Puffer Takifugu rubripes)

Abstract

Studies were made on histopathology of cultured tiger puffer with “Kuchijiro-sho” collected from some fish farms in Nagasaki Prefecture from July to December, 1984.
The fish were characterized by erosion and ulceration of the mouth, dark body coloration and biting aggressively each other. Internally, linear superficial hemorrhage in the liver was commonly observed.
The main histopathological change was found in the large nervous cell at the nucleus of the 8-10th cranial nerve and supramedullary neuron. The change was characterized by formation of some masses in the nucleus and the deformed shape of the nucleus of the large nervous cell and supramedullary neuron. The mass in the nucleus had slight change of coloration for some kinds of stain.
Electron-microscopical examination was made on the nucleus of cranial nerves of the medulla oblongata; as a result, virus-like particles were observed either as a mass-type in the nucleus or as scattering-type on the deformed nuclear membrane.
Judging from the histopathological and electron-microscopical findings, a possibility was suggested that the disease called “Kuchijiro-sho” was caused by virus infection.