Morphological study of the effects of @entity1787 on XXXX lung. II. Long-term exposure.

@entity3617 @entity82 @entity1373 @entity1157 @entity1787 @entity35 @entity528
To evaluate the morphological changes observed in animals after prolonged @entity1787 exposure, 56 male @entity35 were exposed to a high ambient level of @entity1787 (0.5 ppm) 6 hr a day, 6 days a week, for 2, 3, 5, and 12 months and examined by light and electron microscopy. @entity3617 and peribronchitis were observed throughout the exposure periods, and connective tissue around the bronchi thickened as a result of @entity82 . Some bronchiolar ciliated cells were in a @entity528 and others in a reparative phase. Hyperplastic nodules were not found in the bronchioles, but @entity1373 of the bronchiolar epithelium was observed. @entity1373 of lymphoid nodules around small vessels was prominent after 2 months of exposure. After 3 months of exposure, @entity1157 were lined by type 2 cells, and after 12 months, by the bronchiolar epithelium consisting of both ciliated and nonciliated cells. Alveolar macrophages accumulated in the centriacinar alveoli. Fibrous strands were seen to be deposited in @entity1157 after 3 months, and in bronchioles after 5 months. This @entity82 was due to an increment in collagen fibers. The degree of @entity82 increased with the length of @entity1787 exposure.
