Fig. 5

The EdU-labeled clusters (islets) of proliferating adult intestinal epithelial cells during T3-induced intestinal metamorphosis express the adult intestinal stem cell marker Lgr5. Premetamorphic stage 54 tadpoles treated with 10 nM T3 for 0 (A), 3 (B), or 6 days (C) and were sacrificed 1 h after injection with EdU. Cross-sections of the intestine from the resulting tadpoles were double-stained for Lgr5 by in situ hybridization and for EdU. Higher magnifications of boxed areas in (A–C) are shown in (a′–c′). The dotted lines depict the epithelium-mesenchyme boundary (see Fig. 1). Note that the clusters (islets) of EdU labeled cells in the epithelium after 6 days of T3 treatment had high levels of Lgr5 mRNA (c, c′)