Fig. 4. Lymphatic vessel defects in E13 Nrp2 mutant embryos. Transverse sections of E13 Nrp2^+/+ (A,D,G), Nrp2^+/– (B,E,H) and Nrp2^–/– (C,F,I) embryos stained with antibodies recognizing the indicated proteins. Note very similar PECAM staining in the three genotypes (A-C). (D-F) VEGFR3 labels jugular lymphatic vessels (asterisks) present in all three genotypes, as well as lymphatic capillaries in the skin (arrows). Note absence of these capillaries in the Nrp2^–/– embryo (F). (G-I) Higher magnification of adjacent sections corresponding to the boxed area in D-F stained with NRP2 antibodies. The jugular lymphatic vessel (asterisk) is present in all three genotypes. Skin capillaries are NRP2 positive in the Nrp2^+/+ (G) and the Nrp2^+/– (H) embryo. In the Nrp2^–/– embryo (I), only punctuate staining is observed, reflecting the retention of mutant protein in the endoplasmic reticulum. Ao, aorta; Fl, forelimb; H, heart; NT, neural tube. Scale bars: in A, 575 µm for A-F; in G, 230 µm for G-I.