Fig 2. Immunohistochemical examination of the α7 reporter by lung neuronal and neuroepithelial cells.

Panels A through F show images of the α7 reporter tGFP co-expression in lung sections co-stained with various neuronal and neuroepithelial markers. A) Expression of neuropeptide Y (NPY) is observed occasionally in infrequent cell clusters associated with brachial epithelium as reported by others [37]. When present, cells reactive for GFP were adjacent to (arrow head), but did not overlap with, cells expressing NPY (arrow). B) Tyrosine hydroxylase (TH) identifies cells capable of catecholamine synthesis usually in association with neuroendocrine functions. These cell clusters were in part identified by TH immunostaining (arrow heads) and localization to sites of bronchial bifurcation consistent with their identity as Pulmonary neuroepithelial bodies [38] and they contained a mix of GFP stained cells (arrow) and cells co-expressing TH (arrow heads). C) Protein-G product 9.5 (Pgp9.5, aka; ubiquitin C-terminal hydrolase, Uchl1) immunofluorescence in lung sections labeled nerve fibers (arrow head) and occasional solitary cells (inset, arrow). No co-expression of this marker with tGFP was observed. D) Calcitonin-gene related peptide (CGRP) labeled lung sensory fibers did not exhibit detectable tGFP co-expression. E,F) Sensory innervation of the lung by peripherin labeled fibers was prevalent and as shown were particularly prominent in processes of the alveolar compartments that did not label with GFP (arrow). Some of these processes may interact with tGFP-labeled ATII cells (asterisk; see Fig 3). The interaction between AMs that are in contact with alveolar cell linings and peripherin labeled processes is notable (arrowhead). This includes the appearance of specialized neuronal process end points that form a complex of interactions with these stationary AMs. F) Increased magnification shows a strongly tGFP labeled AM (arrows) that is in association with the alveoli and are richly associated with peripherin positive fibers (arrowheads). These process endings often wrap the AMs and multiple process swellings that are interacting with the AM (arrowheads) and in some cases form indentations on the AM (right panel, asterisk). Bars = A-E, 15 microns; F, 5 microns.