Notch inhibition causes lymphatic collecting vessel dilation and decreased coverage of mural cells. (A) VEGFR3 (blue) and SMA (red) costaining of the upper leg skin in P6 neonate treated with PBS (control), αDll4, αNotch1, and ALK1-Fc (10 mg/kg on P2/5). Images show the lymphatic vessels (L) that drain into the popliteal lymph node on either side of a blood vessel (BV). Scale bar represent 200 μm. The smooth muscle actin (SMA) staining in αNotch sample was imaged at a higher exposure setting due the reduction of mural cell coverage of the lymphatic vessels. (B) FITC-lectin (green) and SMA (red) staining of a lymphatic valve in a P6 neonate treated with PBS (control), αDll4, αNotch1, and ALK1-Fc (10 mg/kg on P2/5). Arrow indicates the direction of lymph flow, and scale bar represents 100 μm.