Fig. 5.

Hh pathway activity is critical for TRC maintenance. (A) Representative H&E-stained examples of fungiform papilla from untreated and 2- and 4-wk XL139-treated animals. (B and C) Number of TRC-containing fungiform papillae, and TRC/K8⁺ index estimating relative TRC numbers (Materials and Methods) using immunofluorescence images of whole-mount peeled epithelium from mice treated with vehicle or XL139 for 2 or 4 wk. n = 5, 5, and 7 mice in each group, respectively. (D) Mice treated with XL139 for 4 wk, and allowed to recover for 4 or 8 wk after XL139 withdrawal. n = 7, 8, and 8 mice in each group. (E and F) Immunofluorescence image of whole-mount tongue epithelium stained with K8 (red) and DAPI (blue). (E) Analysis immediately following 4-wk XL139 treatment (no recovery period). Note fungiform papillae are devoid of TRCs (red circles) or show reduced K8⁺ intensity (arrows). (F) A 4-wk XL139 treatment followed by an 8-wk recovery period. K8 staining returned to ∼40% of the fungiform papillae as quantified in D. Fungiform papillae with regenerated TRCs are denoted with yellow circles. [Scale bars: 10 μm (A); 100 μm (E and F).]