Figure 6

Comparison of Hoxa3-lacZ reporter and endogenous Hoxa3 protein expression in VSMCs and ECs of aortic arch. (A) Cross section of aortic arch from adult Hoxa3-lacZ mouse after X-Gal-staining indicates reporter gene expression (blue) in VSMCs (yellow arrows) whereas expression in cells of the endothelial layer (gray arrows) is difficult to discern. (B) Immunohistochemical detection of Hoxa3 in comparable section of adult (8 wk) dorsal aorta; immunolabeling of section with anti-Hoxa3 antibodies and subsequent colorimetric detection (DAB-Ni) reveals expression in ECs (gray arrows) and vascular VSMC (yellow arrows). (C) Multichannel composite micrograph of adult aortic arch section after incubation with immunoreagents specific for Hoxa3 (Cy5-red) and Acta2 (Cy3- green), and Hoechst 33342 for nuclear labeling. The bright red labeling in ECs (gray arrows) confirms Hoxa3 expression. The purple labeling in the media indicates Hoxa3 expression in certain nuclei of VSMCs (yellow arrows). Green label indicates that Acta2 expression is restricted to the media. Lumen is to the left in all panels; space bar: 25 μm.