Fig. 2.

SAM imaging of ovine aorta: tissue wave speed measurements and identification of structural features. (A) SAM image (1 GHz) of an unstained and unfixed aorta cryosection. Elastic lamellae-like tissue sub-structures were clearly evident in high-frequency SAM images (arrows). (B) Mean tissue wave speed was significantly increased in old compared with young animals across the full length of 20 line scans (n = 7 animals per group). (C) The inset region in (A) viewed by: fluorescence microscopy (i) and bright field microscopy following picrosirius red staining (ii). The lamellar structures which are evident in SAM images (A, arrows) correlate with the location of elastin autofluorescence (C(i), arrows) but not with the location of fibrillar collagen (C(ii), arrows). Scale bars = 20 μm. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)