Figure 2.

Video images (top row) of a representative mgR/mgR carotid artery mounted in the testing device (cannulae not shown) and maintained at a pressure of 80 mmHg at its estimated in vivo axial stretch both before (left) and after (right) intraluminal exposure to 7.5 U/mL of pancreatic elastase for 20 min. Note the marked non-uniform increase in diameter after exposure to elastase. Images are to scale with the blue bar representing 700 μm. The red lines show on-line measurement of diameter via a LabView routine. Histological images of VVG-, MTC-, and PSR-stained cross-sections before (left column) and after (right column) treatment with elastase reveal a marked loss of elastin. Note, too, that the smooth muscle layer persisted following elastase despite marked thinning of the media as did the thicker collagen fibres, particularly in the adventitia. Notwithstanding some discontinuities in lamellar organization, mgR/mgR carotid arteries possessed intact elastic fibres that were nearly completely degraded after exposure to elastase. The yellow scale bars represent 50 μm.