Figure 3

Immunostaining of α ₅ nAChR subunits, proSP-C, T1α, and CCSP during the mid-saccular period of lung development (E18.5). α₅ (A, B) was co-expressed with proSP-C (B, arrows) in most ATII cells. α₅ was expressed in non-ATI cells in respiratory airways (C, D arrows) and poorly expressed by T1α-positive ATI cells (C, D arrowhead). α₅ (E) was also expressed by non-ciliated Clara cells in the proximal lung as revealed by CCSP co-localization (F, arrows). Lung sections stained without primary antibodies were negative (not shown). All images are at 40X original magnification and scale bars represent 50 μm.