Epithelial lining of terminal bronchiolus (golden hamster)

Electron microscopy (low magnification). Two major epithelial cell types line the bronchiolus: (1) the ciliated cells with many organelles, and (2) the non-ciliated cells or Clara cells well provided with organelles, especially agranular endoplasmic reticulum and depending on their activity, numerous electron-dense secretory granules (hardly present in this picture). On the basal lamina a N(euro) E(pithelial) B(ody) composed of a cluster of small neuroendocrine cells (3) (belonging to the Amine Precursor Uptake and Decarboxylation cell system so-called APUD cells). The dense-core granules contain among others dopamine or serotonin. Great alveolar cells (so-called pneumocyte II) are represented at (4); interstitium with elastin/collagen/myofibroblasts is found around (5), while (6) represents the alveolar space.