Type II alveolar cell in the lung (rat)

Electron microscopy. At the top the alveolar space (1) is lined by a type II alveolar cell (pneumocyte II) (2) with blunt microvilli. In the cytoplasm the characteristic electron-dense multilamellar bodies (*) and light-stained swollen mitochondria are present. The lamellar bodies are responsible for the vacuolated appearance of these cells, and they give rise to surfactant (phospholipids, glycosaminoglycans, proteins). Thin cytoplasm sleeves (6) of type I alveolar cells are neighboring the pneumocyte II. The collagen fibers are produced by an interstitial (myo)fibroblast (5). Between the pneumocyte II (2) and the capillary (3) a thin interstitium (7) is found consisting of cross-sectioned collagen fibers and cytoplasm of an interstitial cell. (4) represents the endothelium of the capillary.