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Figure 6 Photomicrographs of transmural response to injury, focused on adventitial remodeling. (A) Intense -smooth muscle actin immunoreactivity in the media and outer adventitia at day 4; also perivascular microvessels of the vasa vasorum are positive (arrows). (B) Transmission electron microscopy detail of hypocellular inner adventitia at day 7 illustrating two cells that simultaneously display end-stage apoptotic shrinkage (arrows); see large regions of non-structured matrix (*). (C) Transmission electron microscopy detail of hypercellular outer adventitia at day 7 showing several viable cells with fibroblast-like appearance embedded in dense extracellular matrix. Also, see in the endothelial cell lining a perivascular capillary (*). (D) No signals of OX-62⁺ dendritic cells are found in the media (M) and the broad adventitia at day 4, in contrast to intense OX-62 immuno-staining along the luminal surface. (E) Cell-bound B-cell lymphoma 2 protein signals are exclusively found in the outer adventitia (arrows) at day 4. While demarcation from perivascular connective tissue is not always possible, inner adventitia (*), M, and lumen (L) can be easily distinguished. (F) Transmural heat shock protein 47 expression pattern at day 4. Note the distinct immuno-staining exclusively located in the outer adventitia. Bar = 50 µm (A, D to F); bar = 5 µm (B, C).