Abstract
Fifty-three spontaneous cases of papillary tumor in the bovine urinary bladder encountered in Towada, Aomori Prefecture, were studied histopathologically. The animals involved occupied 3.1% of the cattle kept in this city. A high incidence was shown in bovine strains known for the frequent occurrence of haematuria vesicalis bovis. Macroscopically, localized cancerous growths were found, ranging from small granule to child-fist in size. Property and development of these changes varied from one individual to another. Histopathologically, all the lesions showed papillomatous or papillomatous-cancerous growths derived from the transitional epithelium. They were called papillary carcinoma collectively and classified into types I, II and III on the basis of the degree of malignancy. In 10 cases, weakly basophilic intranuclear inclusion bodies were present in the tumorous epithelial cells. The morphogenesis of these lesions was briefly discussed.
