The alveolar lining contains specialized secretory epithelial cells (type II cells) which produce a surface active lipoprotein. This proposal continues cytochemical studies of the subcellular organization of pulmonary phospholipid synthesis in normal lung and examines the dynamics of surfactant production in chronic lung injury known to produce either hyperplasia and structural changes in the type II cells or the accumulation of phospholipid-rich exudate in alveolar spaces, (alveolar lipoproteinosis). Correlated electron microscopy, autoradiography and biochemical studies of phospholipid turnover will be performed. N-Nitroso N-methyl urethane and asbestos will be used to produce pulmonary fibrosis with epithelial hyperplasia and quartz dust and a drug AY9944 to produce alveolar lipoproteinosis.