Fig. 5. Notch signaling specifies arterial differentiation of vascular smooth muscle cells. (A,B) Smooth muscle myosin heavy chain (smmhc, green) expression in wild-type and Notch3^-/- tail arteries. (B) Arteries of the Notch3^-/- mouse exhibit normal smmhc expression levels. Arrows highlight ectopic vascular smooth muscle cells expressing smmhc in the Notch3^-/- mutant artery. (C,D) Smoothelin (red) (cell nuclei are stained with DAPI, blue) expression in wild-type and Notch3^-/- tail arteries. Smoothelin expression levels are markedly reduced in the Notch3^-/- mutant artery (D). (E-H) ß-galactosidase staining (blue) of tails from wild-type and Notch3^-/- mice heterozygous for a SM22-lacZ transgene. (E,F) Whole-mount view of caudal artery (arrows) in the tail and (G,H) microscopic view through artery (a) and vein (v) demonstrate that ß-galactosidase staining is restricted to arterial vascular smooth muscle cells in control mice and is markedly reduced in Notch3^-/- arteries. Reproduced with permission from Domenga et al. (Domenga et al., 2004). Copyright (2004) Cold Spring Harbor Laboratory Press.