Figure 7. A comparison of taste nerve fibers at E16.5.

Anti-P2X3 (green) and anti-neurofilament (red) antibodies were used to label taste nerve fibers in wild-type (A, D), Bdnf^−/−/Ntf4^−/− (B, E), and TrkB^−/− mice (C, F). While only wild type mice had P2X3-positive neural buds innervating fungiform placodes (A), both hybrid Bdnf ^−/−/Nt4 ^−/− mice (B) and TrkB ^−/− mice (C) had P2X3 positive fibers penetrating the epithelium of fungiform placodes. Neurofilament-positive and P2X3-negative innervation was present in the epithelium of all three genotypes (D, E, F). The scale bar in C and F = 20 µm and applies to A–C or D–F, respectively.