Normal lymphatic development in double-heterozygous nrp2^+/−vegfr2^+/− mice. (A) EGFP staining of mesenteric vessels in a heterozygous vegfr2-egfp mouse pup at P0. Note green fluorescence in capillaries covering the surface of the duodenum and in mesenteric arteries, veins, and lymphatic vessels. D, duodenum; A, mesenteric arteries; V, veins; L, lymphatic vessels. (B–B″) EGFP–LYVE-1 double staining of tail skin at P1. Note Flk-1–EGFP expression in a lymphatic vessel sprout (asterisks) and in filopodia-extending tips (arrows). (C) Quantification of lymph vessel branch points. Error bars indicate SEM. (D–D″) Normal appearance of lymphatic vessel sprouts (asterisks) and filopodia-extending tips (arrows) in P1 tail skin in double-heterozygous nrp2^+/−vegfr2^+/− mice. (E and F) Lower magnification views of LYVE-1–positive lymphatic vessels in wild-type (E) and nrp2^+/−vegfr2^+/− dorsal trunk skin. WT, wild type. (F’–F″) Flk-1/VEGFR2-EGFP–LYVE-1 double labeling. OV, overlay. Bars: (A) 200 µm; (B–D″) 50 µm; (E–F″) 200 µm.