title: The epizootiology and pathogenesis of thyroid hyperplasia in coho salmon (Oncorhynchus kisutch) in Lake Ontario.
abstract: The thyroid glands of coho salmon collected at different stages of their anadromous migration exhibited progressive and extensive hyperplasia and hypertrophy. The incidence of overt nodule formation rose from 5% in fish collected in August to 24% in fish collected in October. The histological picture of the goiters was similar to that found in thiourea-treated teleosts and thiouracil-treated mammals. There was a concomitant, significant decrease in serum thyroxine and triiodothyronine values between September and October (thyroxine, 1.0+/-0.3 mug/100 ml and 0.4 mug/100 ml in September and October, respectively; triiodothyronine, 400.3+/-51.6 ng/100 ml and 80.2 ng/100 ml in September and October, respectively) and marked hypertrophy and hyperplasia of thyrotrophs. These data indicate a progressive hypothyroid condition which, although it may be linked to iodide deficiency, may well be enhanced by other environmental factors. The evidence for involvement of other factors is discussed.
mesh_terms: D000818:Animals; D002170:Canada; D005393:Fish Diseases / Q000097:blood / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology; D006042:Goiter / Q000209:etiology / Q000473:pathology / Q000662:veterinary; D006965:Hyperplasia / Q000209:etiology / Q000473:pathology / Q000662:veterinary; D007455:Iodine / Q000172:deficiency; D010902:Pituitary Gland / Q000473:pathology; D012474:Salmon; D012621:Seasons; D013959:Thyroid Diseases / Q000097:blood / Q000453:epidemiology / Q000662:veterinary*; D013961:Thyroid Gland / Q000473:pathology; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014873:Water Pollutants / Q000009:adverse effects
chemical_list: D014873:Water Pollutants; D014284:Triiodothyronine; D007455:Iodine; D013974:Thyroxine