Ultrastructure and origin of adenocarcinomas detected in the lungs of three cows.

Three types of bovine adenocarcinoma were found in the lungs of 3 cows. Case 1 was a well differentiated adenocarcinoma with mucin granules and microvilli with core filaments seen ultrastructurally. In Case 2, the neoplastic tissue showed a sarcoma-like growth with scattered tubular structures. Many cilia were observed in the tubular structures and a few cilia were found in the anaplastic tissues. Case 3 had epithelial and undifferentiated tissues. A few mucin granules and cilia were observed in the tumours in both lung and kidney. The relationships between these neoplastic cells and bronchial epithelial cells are discussed.