Studies on ichthyophonus disease of fishes - I : Rainbow trout fry

1) ニジマス稚魚のイクチオフォヌス症を病理組織学的に検討した。 2) イクチオフォヌスは稚魚に全身感染を起こしていた。組織に現われたイクチオフォヌスは孤在性の多核球状体の姿を示すことが最も多いが, 発芽中のものや糸状体に姿をかえたもの, その糸状体内で糸状体胞子を形成しているものもみられた。 3) 宿主のイクチオフォヌスに対する炎症反応は大単核細胞の繁殖性炎で特徴づけられた。Ichthyophonus disease had broken out among rainbow trout fry in July 1975, and after that a fish group containing diseased fish had been kept for one year. Hence authors observed histopathologically diseased fry in the initial stage of the epizootic and moribund yearling fish in the clonic condition. This paper deals with the result of the observation on diseased fry. Ichthyophonus invaded the various tissues and took the shape of multinucleate spherical or hyphal body. The smallest form was binuclear bodies. The multinucleate-spherical bodies were walled by the thick cell wall and contained many nuclei with a large nucleolus and granular cytoplasm forming the mesh-work. Their size was varied and became to large with growth and could be measured in the diameter 7 to 10µ in the binuclear bodies and 20 to 140µ in multinucleate spherical ones. The hyphal bodies often extended from the spherical body and produced hyphal spores with one to ten nuclei, whose hematogenous dissemination caused systemic infection. The inflammatory reaction against Ichthyophonus was characterized by mononuclear-cellular proliferation with giant cell formation and fibroblasts proliferation