Title: Elastic fibers in the lung
Stain orcein, human. At the left (1) several alveoli (A) are depicted with a faint staining of cellular elements. The elastic fibers within the alveoli are stained reddish-purple. At the right (2) a high magnification of a tangential-sectioned alveolus shows the thicker bundles as well as very thin branches of elastic fibers.
Title: The alveolar tip in lung tissue
Electron microscopy, adult human. The lung tip is covered by a flattened alveolar cell type I (↓1) and a similar neighbouring bulging one with nucleus (2).
In the alveolar tip amorph elastin (5) appears more electron-dense than the collagen fibers (Col) and is interwoven with it.
Small foci of calcifications are found common in ageing lungs (4);
(3) indicates an elastoblast in close association with the surrounding elastin as well as with bundles of collagen (Col).
Title: Elastin close near the alveolar tip in lung tissue
Electron microscopy, adult human. The alveolar tip in the alveolar spaces (Alv) is covered with flattened type I alveolar cells (2). The arrows at (↓1) indicate the junctions between these flattened cells. The amorph elastin (*) in the alveolar tip appears more electron-dense than the collagen fibers (Col). Note the characteristic dark dots and bundles of microfibrils (3) (among others fibrillin) associated with elastin.
Keywords/Mesh: respiratory system, lung, alveolus, alveolar tip,
type I alveolar cell, pneumocyte I, myofibroblast, elastoblast, collagen, elastic fiber, elastin, microfibril, elastin-associated protein, histology, electron microscopy, POJA collection