Slow-cycling stem cells are responsible for junctional epithelium (JE) regeneration. (A) A schematic showing the experiment design. Mice were first injected with tamoxifen to label Wnt-responsive cells and then treated with 5-fluorouracil (5-Fu) for 7 d. (B) Morphology and (C) distribution of the progeny of Wnt-responsive cells were examined. Four days after the last 5-Fu injection, (D) morphology, (E) distribution of the progeny of Wnt-responsive cells, and (F) 5-ethynyl-2′-deoxyuridine–positive (EdU+ve) cells were examined. Seven days after the last 5-Fu injection, (G) morphology, (H) the progeny of Wnt-responsive cells, (I) laminin 5 expression, and (J) EdU+ve cells were examined. (K, L) Collagen fiber, (M, N) tartrate-resistant acid phosphatase (TRAP) activity, and (O, P) alkaline phosphatase (ALP) activity were compared between the 5-Fu group and intact group. (Q) Quantification of bone resorption and formation activity (n = 6). The bone resorption activity is expressed as the number of osteoclasts per bone surface. The bone formation activity is expressed as the pixels of ALP to the total pixels. The data were expressed as mean ± SD. Abbreviations: as before and ALP, alkaline phosphatase. Scale bars: 50 µm.