Representative photomicrographs showing nodose neurons retrogradely labeled from the trachea with fluorogold (FG) overlaid with immunoreactivity for (A) neurofilament (NF), (B) calbindin, (C) calretinin, and (D) parvalbumin (low magnification showing no immunostaining). The arrow heads in panels (B) and (C) point out calbindin and calretinin-labeled nerve fibers, respectively. The inset (B') shows two nodose neurons from an adjacent region of the ganglia that were immunoreactive for calbindin. The scale bar in (B') represents 50 μm. The scale bar shown in panel D represents 50 μm in panels (A-C) and 250 μm in panel (D).