Fig. 3: BMP signaling regulates villus length.

a Immunofluorescence staining of Ki67 in control and Villin^CreERT2; Bmpr1a^flox/flox (Bmpr1a cKO) mice at day 12 post-tamoxifen injection (dpi). Quantification of villus length and cell number from the proximal to the distal small intestine and Ki67⁺ cells in the jejunum. N = 3 mice/group. Scale bars, 200 µm. b Immunofluorescence staining of Ki67 in control and Villin^CreERT2; Smad4^flox/flox (Smad4 cKO) mice at 12 dpi. Quantification of villus length and cell number from the proximal to the distal small intestine, and Ki67⁺ cells in the jejunum. N = 3 mice/group. Scale bars, 200 µm. c Immunofluorescence staining of Ki67 in control and Cagg^CreERT2; Grem1^flox/flox (Grem1 cKO) mice at 12 dpi. Quantification of villus length and cell number from the proximal to the distal small intestine, and Ki67⁺ cells in the jejunum. N = 3 mice/group. Scale bars, 200 µm. d Immunofluorescence staining of Ki67 and E-cadherin in control and Bmpr1a cKO mice at 42 dpi. Quantification of villus length from the proximal to the distal small intestine. N = 3 mice/group. Scale bars, 500 µm. In (a–c) the white arrows indicate the apex of the villus, and the original blue color of DAPI staining in microscopy images has been adjusted to green for better visualization. This adjustment applies uniformly across the entire image. Quantification of villus length and cell number was analyzed by two-way ANOVA with Tukey’s multiple comparison test; Quantification of Ki67⁺ cells was analyzed by unpaired t-test (two-sided). Data represent mean ± SD.