Histopathological Observations on an Intense Congestion of the Gills in Cultured Japanese Eel, Anguilla japonica

Abstract

A new disease of Anguilla japonica which is characterized by an intense congestion of the gill filaments was histopathologically studied. In all the diseased eels studied the central venous sinuses and all other venous vessels of the gill filaments were observed to be filled with blood and markedly inflated.In part of the gill filaments it was observed that the blood once filled the central venous sinuses and other venous vessels had partly or almost entirely flowed out, leaving a marked dilatation of them. Destructive lesions were not observed in any part of the gill vasculature. No evidence of obstruction was observed in any part of the arterio-arterior vasculature. Arteriovenous anastomoses were observed to maintain the normal structure. The intense congestion of the arterio-venous vasculature in diseased eels is of essentially unknown etiology, but some physiological disturbance in cardiovasculature functions may be involved in the causation.