A peculiar mode of formation of the surface lining layer in the lungs of Salamandra salamandra.
The pneumocytes of the larva of Salamandra salamandra contain numerous lamellar bodies and their precursors: electron-dense bodies at various stages of development. Both lamellar bodies and electron-dense bodies occur inside the fluid-filled lung. The former are spherical or bell-shaped and possess concentrically arranged smooth membranes, 8 nm thicks; the latter have paracrystalline cores composed of alternatively oriented clear and dark striations (3 . 6--3 . 9 nm and 2 . 6--3 . 6 nm, respectively). On all sides such cores separate membranes, which assume a concentric orientation. No tubular myelin was observed in any phase of the transformation of lamellar bodies and electron-dense bodies into the surface lining layer. Fixation of the lungs of adult individuals with tannic acid-containing fixative visualized the surface lining layer, but not tubular myelin.
D000818:Animals; D004848:Epithelium / Q000648:ultrastructure; D007425:Intracellular Membranes / Q000648:ultrastructure; D008168:Lung / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009940:Organoids / Q000648:ultrastructure; D012454:Salamandra / Q000033:anatomy & histology* / Q000254:growth & development