Fig. 5. Lymphatic vessel defects in the skin of developing Nrp2 mutant mice. (A,B) Whole-mount X-gal staining of E15 dorsal skin. Note the absence of X-gal-positive vessels in the Nrp2^–/– (B). (C-H) Transverse sections through the dorsal skin of E17 embryos stained with anti-VEGFR3 (C,E,G) and PECAM (D,F,H). Note the absence of lymphatic vessels in the Nrp2^–/– dermis (C, bottom) compared with Nrp2^+/+ and Nrp2^+/– dermis (C, top; G). PECAM staining shows no difference between the three genotypes (D,H). (E,F) Comparison of VEGFR3 and PECAM staining of a Nrp2^–/– dermis at higher magnification. Note weaker PECAM staining of VEGFR3-positive vessels (asterisks) as compared with arteries (A) and veins (V). Note also that the lymphatic vessels that form are located in a slightly deeper position at the border of the dermis and the connective tissue (compare E with C, G). (I,J) The comparison of VEGFR3 and -actin staining shows that lymphatic vessels (asterisks) are not surrounded by smooth-muscle cells, while arteries and veins are (A, V, arrows). Scale bars: in A, 230 µm for A,B; in C, 180 µm for C,D,G,H; in E, 70 µm for E,F; in I, 20 µm for I,J.