Microscopical findings from moribund Kuruma shrimp larvae, Penaeus japonicus, showed no evidence of any polyhedral inclusion bodies in either squash preparations of the affected mid-gut gland or in preparations stained by Vago-Amargier's method. Pathological changes were remarkable cellular necrosis and collapse of mid-gut gland. It was noted that nuclear hypertrophy and collapse always followed these cellular changes. Electron microscopical findings showed cytoplasmic collapse of mid-gut gland cells and the nuclear hypertrophy resulting in karyorrhexis, as well as virions and incomplete viral particles re presenting virogenic stages in the affected nuclei. The average length and diameter of virions was 310 nm and 72 nm respectively, and length of the nucleocapsids was 250 nm. Infectivity trials carried out employing oral and water borne inoculations revealed high cumu lative mortality to healthy shrimp larvae.

ABSTRACT:Necropsy and histopathologic examination of three Great Cormorants (Phalacrocorax carbo) shot in Niigata, central Japan, revealed goitrous changes in the thyroids. Thyroids had a hypertrophic follicular epithelium, loss or deficiency of luminal colloid, occasional small follicles suggesting hyperplasia, and occasional collapsed follicles. Irregularly shaped follicles were frequent, and hyperemia, deposition of dark pigment, and sporadic lymphoid aggregates were also seen. Chemical analysis simultaneously conducted showed higher than normal levels of dioxins in the liver, muscle, and fat, i.e., polychlorinated dibenzo-dioxins, polychlorinated dibenzo-furans, and coplanar polychlorinated biphenyls. The present results, together with those of relevant previous studies, strongly suggest an association between these pollutants and thyroid lesions in the Great Cormorant.