Ultrastructural study of naturally occuring ovine pulmonary adenocarcinoma in Fars province, Iran

Document Type: Full paper (Original article)

Authors

1 Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

2 Graduated from School of Veterinary Medicine, Shiraz University, Shiraz, Iran

Abstract

Ovine pulmonary adenocarcinoma (OPA) was studied in the lungs of 15 naturally-affected sheep (9 with
classical and 6 atypical lesions) by transmission electron microscopy. Two lung samples from normal sheep
were used to develop the ultrastructural criteria. Pathologic lesions consisted of focal-multifocal to coalescent
nodules or masses in the cranioventral or diaphragmatic lobes. Ultrastructural characteristics of tumor cells in
the alveoli and bronchioles allowed categorization of these cells into three groups; neoplastic alveolar type
(AT)  Пcells in the alveoli contained numerous cytoplasmic lamellar bodies, well developed rough endoplasmic reticulum and glycogen particles; neoplasticclara cells in the bronchioles contained apical
electron-dense granules and well-developed smooth endoplasmic reticulum; undifferentiated tumor cells in
the alveoli and bronchioles lacked characteristic lamellar bodies or electron-dense granules. Neither complete virions nor viral inclusions were seen in the neoplastic cells. In the present study, there were no
ultrastructural differences in the neoplastic cells betweenclassical and atypical forms. It seems that type II
pneumocytes and clara cells are the origin of the neoplasia in the alveoli and bronchioles, respectively.

Keywords