Title: Air-Blood barrier in the lung
Scheme electron microscopy, human.
(1, ↓) Represents type I pneumocytes lining alveolar spaces (A). Cell (2) represents a free alveolar macrophage. The type II pneumocyte (3) is adherent to type I pneumocyte extensions (note junctional connection), and contains multilamellar bodies (surfactant). A myofibroblast (4) is located in the interstitium (note surrounding cross-sectioned collagen fiber dots), and (*) indicate elastin. (5, ↓) Indicate endothelial cells within the capillaries. (6↔) Indicates the thin-walled area of the air-blood barrier.
Keywords/Mesh: respiratory tract, lung,
alveolus, Air-Blood barrier, alveolar cell,
type I alveolar cell, type I pneumocyte,
type II alveolar cell, type II pneumocyte,
multilamellar body, alveolar macrophage,
interstitial cell, interstitium, capillary, histology, electron microscopy, POJA collection
Title: Type II alveolar cell in the lung
Electron microscopy, rat. At the top the alveolar space (1) is lined by a type II alveolar cell ( pneumocyte II) (2) with thin 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 neighbouring 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.
Title: Multilamellar bodies of type II alveolar cell in the lung
Electron microscopy, mouse. The cytoplasm of the type ll alveolar cell (pneumocyte II) contains characteristic electron-dense multilamellar bodies (*) in different maturing stages. The lamellar bodies are responsible for the vacuolated appearance of these cells, and they give rise to surfactant (phospholipids, glycosaminoglycans, SP-A,B,C and D-protein). The pulmonary surfactant coats the alveolar surface, lowers the surface tension and plays also a role in the lung immune defense system.