Figure 2.
Collecting lymphatic vessels are hyperplastic and unvalved in ephrinB2ΔV/ΔV mice. (A) Chylothorax in an ephrinB2ΔV/ΔV mutant mouse. Gross dissection of the chest cavity of a P6 ephrinB2ΔV/ΔV mutant cadaver showing chest cavity filled with chyle (★). (h) Heart. (B-E) X-Gal staining in heterozygous ephrinB2LZ/+ reporter mice. In addition to strong expression in the arterial endothelium and SMCs, ephrinB2 promoter activity is detected in the endothelium of collecting lymphatic vessels surrounding the ischiatic vein (B), in the skin (C), mesentery (D), and thoracic duct (white arrowhead, E). (B-D) While venous endothelium (V) is negative for ephrinB2 expression, the SMCs surrounding larger veins are positive (see also Supplementary Fig. S2). Luminal valves are indicated with black arrows. (L) Lymphatic vessel; (A) artery; (V) vein; (DA) dorsal aorta. (F-O) Fluorescent lymphoscintiography of the collecting lymphatic vessels surrounding the ischiatic vein (F,G) and of the thoracic duct (N,O) after high-molecular-weight FITC-dextran injection into the hindlimb footpad of wild-type (F,N) and ephrinB2ΔV/ΔV mutant (G,O) mice. X-Gal staining of lymphatic vessels in VEGFR3LZ/+ mice of ischiatic vein region (H,I), collecting lymphatic vessels of the skin (J,K), and mesenteric lymphatic vessels (L,M) of the indicated genotypes (top). The collecting lymphatic vessels are hyperplastic in the mutant mice (G,I,K) and lack the luminal valves present in wild-type mice (arrows in panels F,H,J,L). The thoracic duct is indicated by white arrowheads in panels N and O; the leakage and reflux of FITC dextran dye into the side branches in ephrinB2ΔV/ΔV mutant mouse is indicated by white arrows in O. Bars: B-D,F-M, 200 μm; E,N,O, 500 μm. Ages of the mice: B,F-I,N,O, P10; D,E,L,M, P5; C,J,K, P1.