Figure 1.

Regions of the lung, their potential stem cell niches and related lung diseases. Left: Regions of the bronchial tree are shown from proximal (top) to distal (bottom). Middle: The normal histology of regions highlighted in the blue boxes are shown, indicating putative, region‐specific stem/progenitor cells and their niches. Right: Lung diseases shown are (a): cystic fibrosis with mucus plugging and abnormal submucosal gland duct (arrow), (b): chronic obstructive pulmonary disease with squamous metaplasia (solid arrow) and mucus metaplasia (dotted arrow), (c): pulmonary arterial hypertension with intimal thickening (arrow), (d): acute respiratory distress syndrome with hyaline membranes (arrow), inflammation, and edema, (e): idiopathic pulmonary fibrosis with fibrotic foci (arrow) and extensive lung remodeling and (f): bronchopulmonary dysplasia with alveolar simplification. Abbreviations: ARDS, acute respiratory distress syndrome; BASC, bronchioalveolar stem cell; BPD, bronchopulmonary dysplasia; CF, cystic fibrosis; COPD, chronic obstructive pulmonary disease; IPF, idiopathic pulmonary fibrosis; LNEP, lineage‐negative epithelial stem/progenitor cell; PAH, pulmonary arterial hypertension; T2*, type 2 alveolar cell*.