Non-specific esterase in the alveolar tissues of hamster lung: an electron microscope study.

The fine-structural localization of non-specific esterase was studied in the alveolar tissues of hamster lung by incubating sections of glutaraldehyde-fixed tissues in a medium containing lead ions and thiolacetic acid. The nature of the reactive enzymes was determined by exposing some sections to different inhibitors. The results showed that non-specific esterase activity was strongest in the inclusion bodies and vacuoles of alveolar macrophages. Weaker reactions were detected in the inclusions of type II pneumonocytes, the specific granules of eosinophilic and polymorphonuclear leucocytes, and the dense bodies of type I pneumonocytes and septal fibrocytes. It is suggested that the esterase within the alveolar macrophages and type II pneumonocytes may be responsible for the catabolism of surface-active lipids.