Immunohistochemical detection of ephrinB2 in serial sections of human arteries. Most endothelial cells from placenta arteries strongly express ephrinB2 (A,C, ⬆), whereas those in arteries with a reduced lumen-to-media ratio only weakly stain for ephrinB2 (A,C, ▴). Endothelial cells in adult coronary arteries show a markedly diminished expression of ephrinB2 (B,D, ⬆; endothelial cell staining intensity in panels C,D). Smooth muscle cells located in the media of adult coronary arteries are partially positive for ephrinB2 (D; scale bar represents 100 μm).