Fig. 2. Nrp2 expression becomes restricted to embryonic lymphatic vessels and, at low levels, veins. Transverse adjacent sections through the neck of an E13 embryo stained with antibodies against the indicated proteins. (A) NRP2 is expressed in the ventral part of the neural tube (NT) and sympathetic ganglia (SG), as well as in mesenchyme surrounding the developing vertebrae (V) and trachea (T). In the vascular system, arteries (A) are negative, the cardinal veins (cv) are weakly positive and jugular lymphatic vessels (asterisks) are strongly positive. (B) VEGFR3 is expressed in the jugular lymphatic vessels (asterisks). (C) PECAM staining reveals abundant blood-vascular capillaries, arteries (A) and the cardinal veins (cv). Note expression on lymphatics at this developmental stage (asterisks). (D,E) High-power magnification of the cardinal vein (cv) and the adjacent lymphatic vessel (asterisk). Note weak NRP2 expression in the cv (arrows). DRG, dorsal root ganglion; oe, oesophagus. Scale bars: in A, 175 µm for A-C; in D, 35 µm for D,E.