Ultrastructural analysis of the type II epithelial cells and free alveolar cells in experimental lung emphysema.

Ultrastructural changes in alveolar epithelial cells and free alveolar cells after a single intratracheal papain injection were studied. The experiment was carried out on male Wistar rats, of 180-220 g body weight. The animals were sacrificed 1, 7, 14 and 28 days following proteolytic enzyme administration. The study revealed that the development of emphysematous changes in the rat lungs was accompanied by alterations in the epithelium of alveoli. In early stages of emphysema (up to 1 week) destructive changes predominated in the epithelial cells. In later periods an increased number of type II pneumocytes were seen and focal accumulation of elastic and collagenic fibres was noticed in alveolar septa. Correlation was found between changes in ultrastructure and number of type II cells, alveolar macrophages and neutrophils and alterations in the interstitium of alveolar septa.