<i>Lgr5</i> expression during taste papillae development.

<p>(A–D) Whole mount EGFP fluorescence of <i>Lgr5^EGFP-ERCre/+</i> mice tongues at E13.5 (A), P0 (B), P12 (C) and P20 (D). FG, fungiform papillae; FL, foliate papillae; CV, circumvallate papillae. (E–R) Tongue sections of <i>Lgr5^EGFP-ERCre/+</i> mice. (E, F) GFP staining of <i>Lgr5^EGFP-ERCre/+</i> tongue at E13.5, with Prox1, a placode marker (F). (G, H) GFP staining of <i>Lgr5^EGFP-ERCre/+</i> FG papillae at P0.5, with CK8 (G) and Prox1 (H) co-staining. (I) GFP (left panel) and CK8 (right panel) staining on the same section from <i>Lgr5^EGFP-ERCre/+</i> FG papillae at P50, demonstrating that <i>Lgr5</i> is not expressed within adult FG papillae. (J–L) GFP staining of <i>Lgr5^EGFP-ERCre/+</i> CV papillae at P0.5, with CK8 (K) and Prox1 (L) co-staining. (M–R) GFP staining of <i>Lgr5^EGFP-ERCre/+</i> CV papillae at P50, with indicated markers (N–R). Non-specific signal is detected at apical tips of taste receptor cells and surface layers of the tongue (asterisks; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066314#pone.0066314.s001" target="_blank">Fig. S1</a>). (M) <i>Lgr5</i> is locally expressed in basal layers in trenches of the CV papillae (arrowheads), but not outside CV papillae. (O–R) Sections were stained with GFP (upper panel) and indicated antibodies (middle panel). Merged images are shown in the lower panels. Arrowheads point to double positive cells. Scale bars = 20 µm (G–I, K, L, N–R), 50 µm (E, F, J, M), and 500 µm (A–D).