(A) Loss of DLL4 protein in Dll4ΔLEC lacteals. Whole-mount immunofluorescence staining for DLL4 (red) and VEGFR3 (green) in WT and Dll4ΔLEC lacteals. (B) Efficient loss of Dll4 mRNA in Dll4ΔLEC LECs. Dll4 expression (mean ± SD) in sorted intestinal LECs from WT and Dll4ΔLEC mice analyzed by RT-qPCR; n = 3. (C) Dll4 inactivation reduces lacteal filopodia (LYVE1, red). LYVE1 is intentionally overexposed to highlight lacteal filopodia (white dots). Filopodia/lacteal (mean ± SD) of control and Dll4ΔLEC mice 10 weeks after tamoxifen injection; n = 4–5. (D) Lacteals are shorter in Dll4ΔLEC mice. Representative images of villus blood capillaries (PECAM1, green) and lacteals (LYVE1, red) from control and Dll4ΔLEC mice after 10 weeks of Dll4 deletion. Lacteal length (mean ± SD) binned for given lengths 3 weeks (top) and 10 weeks (bottom) after tamoxifen injection; n = 3. Scale bars: 10 μm, A; 20 μm, C; 100 μm, D. *P < 0.05, ***P < 0.001, 2-tailed unpaired Student’s t test.