Title: The terminal part of the airway: alveoli
Electron microscopy, dog. (A) indicate alveoli; (C) indicate capillaries. (1) Type I alveolar cell (pneumocyte I, squamous alveolar cell); (2) type II alveolar cell (pneumocyte II, great alveolar cell); (3) alveolar macrophage. (4) endothelium of capillary.
Title: Capillary system of lung alveoli
Stain by injecting the specimen with trypan blue in gelatin via the pulmonary system, cat. In a tangential view the blue-stained dense capillary plexus surrounding each alveolus is well depicted.
Title: The alveolus and Air-Blood barrier in the lung
Electron microscopy, rat. The alveolus (1) is lined by a thin extension (2) of the alveolar epithelial cell type I (2), the pneumocyte I and the thin endothelium (3) of the capillary filled with erythrocytes (4) and blood platelets (5). The thin-walled air-blood barrier (↔) consists of the transition from endothelium→ a common single basal lamina →pneumocyte I. Note that oxygen diffusion also takes place at the other transitions, the so-called thick walled areas. Thin-walled areas are most favourable to gas exchange and alternate with thick-walled areas (thick line, ▬) consisting of supporting fibers, extracellular matrix and cells of the alveolar framework that separate the alveolar epithelium from the capillaries.
Title: The air-blood barrier in the lung
Electron microscopy, rat. The alveolar space (1) and the capillary space (2) (with part of an erythrocyte, 3) are separated from each other respectively by cytoplasm of endothelial cell (5), the common basal lamina (6) with a lamina densa (6a) and the type I alveolar cell (4, pneumocyte I). Note numerous transport vesicles (pinocytosis, diacytosis) in (4) and (6).The air-blood barrier consists of the layers (4) + (6) + (5). Thin-walled areas are most favourable to gas exchange and alternate with thick-walled areas (not shown here) consisting of supporting fibers, extracellular matrix and cells of the alveolar framework that separate the alveolar epithelium from the capillaries.
Keywords/Mesh: respiratory tract, lung, alveolus, capillary, alveolar cell, pneumocyte I, alveolar cell type I, pneumocyte II, alveolar macrophage, Air-Blood barrier, histology, electron microscopy, POJA collection