Abstract
Type II alveolar epithelial cells show high levels of acid phosphatase, aryl sulfatase B and β-glucuronidase activities. In formalin- and glutaraldehyde-fixed rabbit lung acid phosphatase and aryl sulfatase B activities were demonstrated in the cytoplasmic inclusion bodies, supporting their identification as lysosomes. Type II cells differ from alveolar macrophages in their levels of hydrolase activity and the fine structure of their active sites.