Fig. 1. NRP2 expression in the vascular system of E10 mouse embryos is restricted to veins. In situ hybridization with the indicated antisense riboprobes to sections of E10 mouse embryos. (A) Nrp2 is expressed in the floor plate (asterisk), neurons of the ventral spinal cord (arrowhead), dorsal root ganglion (DRG, arrow), sympathetic ganglion (sg), somitic tissue (S) and dorsal aspect of the forelimb (Fl). (B) Overlapping, but distinct expression of Nrp1, which is expressed in neurons of the ventral spinal cord (arrowhead) and DRG (arrow). Asterisk indicates floor plate. (C) Vegfr3 expression is restricted to the vascular system. (D-F) Higher magnification of the sections in A-C. Nrp2 is expressed in the cardinal vein (cv, D), while Nrp1 shows complementary expression in the aorta (Ao, E) and surrounding mesenchymal cells. (F) Vegfr3 expression is low in EC of the aorta and cardinal vein, but high in small vessels that appear to branch from the cardinal vein (arrows in F). NT, neural tube. Scale bars: in A, 200 µm for A-C; in D, 95 µm for D-F.