The OS and the related Cornell C strain are interesting animal models for the study of the etiology of autoimmune thyroiditis. They are especially valuable for studying the etiologic role of thyroid abnormalities and abnormalities in the processing of iodine. Limitations of the model are the scarcity of immunological reagents for chickens, the absence of avian cloned thyroid-specific genes, minimal amounts of microsomal antibody and some differences between OS chickens and Hashimoto's patients in the types of thyroid abnormalities observed.