MORPHOLOGY OF SPONTANEOUS AND INDUCED-TUMORS IN THE BRONCHIOLO-ALVEOLAR REGION OF F344 RATS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 2  (1-2) , 53-57
Abstract
The morphology of spontaneous and chemically-induced metastasizing carcinomas and adenomas in the bronchiolo-alveolar region of F-344 rats was studied. Histologically, the tumors were tubulo-papillary. Ultrastructurally, they consisted of cells which formed and secreted osmiophilic lamellated inclusion bodies, a marker of alveolar type II cells. Mitotic tumor cells also demonstrated such bodies. No cells of bronchial or bronchiolar origin were found in the tumors. In F344 rats, lung tumors located in the bronchiolo-alveolar region apparently consist of alveolar type II cells exclusively and are, therefore, alveolar cell adenomas and caromas, respectively. [The chemical carcinogens included N-nitrosomethylurethane, N-nitrosoheptamethyleneimine, tris(2,3-dibromopropyl)phosphate, 2,5-dithiourea and 3-nitropropionic acid.].