Synonyms: AT2 cell | ATII cell | TII (type II) | alveolar epithelial cell, type II | alveolar epithelial type II cell | alveolar type II cell | cuboidal type II cell | granular pneumocyte | lung type 2 cell | type 2 alveolar epithelial cell | type 2 pneumocyte | type II alveolar cell | type II alveolar epithelial cell
Definition: A cuboidal-like, alveolar epithelial cell that synthesizes, stores, secretes, and recycles pulmonary surfactant phospholipids and proteins, substances that reduce the surface tension in the alveolus. Pulmonary surfactant is stored in lipid-rich lamellar bodies, a distinctive feature of this cell type. The type II pneumocyte is also capable of cell division and can repopulate the alveolar epitheium after injury, differentiating into type I pneumocytes. Although this cell type covers less than 5% of the alveolar surface, it represents 60% of all alveolar epithelial cells.