Figure 5

Immunostaining of α ₅ nAChR subunits, proSP-C, T1α, and CCSP during the mid-alveolar (PN10) and near the conclusion of the alveolar period (PN20) of lung development. α₅ (A, C) expression at PN10 persisted in distal lung ATII cells that express proSP-C (B, arrows) and ATI cells that express T1α (D, arrows). This period also coincided with undetectable α₅ expression in the proximal lung (E) revealing no co-localization with CCSP (F, arrowhead). At PN20, α₅ (G, I) expression remained detectable in ATII cells that express proSP-C (H, arrows) and ATI cells that express T1α (J, arrows). This period agreed with a return to robust α₅ expression in the proximal lung (K, arrow), most notably by Clara cells that express CCSP (L, arrow). Lung sections stained without primary antibodies were negative (not shown). All images are at 40X original magnification and scale bars represent 50 μm.