Figure 3.

Wnt signaling regulates proliferation of cultured intestinal epithelium. (a–c) Dkk1 inhibits intestinal epithelial growth. (a) Stereomicroscopy and histology of Dkk1-treated jejunal cultures. Cultures were maintained with Dkk1 (50 μg ml⁻¹) for 7 d followed by incubation without Dkk1 for an additional 28 d. (b) Dose-dependent inhibition of jejunal sphere growth by Dkk1. Cultures were treated with various concentrations of Dkk1 on days 0–7. The number of spheres was counted. Error bars indicate s.e.m.; n ≥ 7. *P < 0.05 versus vehicle control (VC); **P < 0.01 versus VC. (c) H&E and PCNA staining after Dkk1 treatment of pre-established intestinal cultures. Cultures were preestablished for 28 d followed by Dkk1 treatment for 5 d. (d–h) RSpo1-Fc treatment of intestinal epithelial cultures. (d) Stereomicroscopic visualization and PCNA staining of the jejunal cultures. RSpo1-Fc was included once weekly until harvest at day 29. (e) H&E and PCNA staining of colon cultures that were preestablished for 28 d followed by RSpo1-Fc treatment for 5 d. (f–h) Proliferative activity (f), number (g) and size (h) of jejunal and colon spheres. RSpo1-Fc was included once weekly for 5 weeks (f) or from days 0–7 (g,h). Error bars indicate s.e.m.; n ≥ 7. *P < 0.05 versus VC; **P < 0.01 versus VC.