Figure 1

Representative micrograph showing an AE2 cell with normal blood-air barrier in a control lung. The ultrastructure of the AE2 cell is characterized by the existence of lamellar bodies (LB). A luminal surface to the alveolar space can be distinguished from the baso-lateral surface adjoining the basement membrane. Furthermore, mitochondria (M), the endoplasmatic reticulum (ER), the nucleus (N) as well as the nucleolus (Nu) are visible. The alveolar space (Alv) and the capillary lumen (Cap) are separated by the very slim and intact blood-air barrier consisting of the alveolar epithelial cells, basement membrane and capillary endothelial cells. Scale bar: 5 μm.