Fig. 1.

Schematic illustration of the heart left ventricle shows the locations of sample dissection (A, B) and verifications of elastin signal specificity (C–F). Dashed lines (B) label three regions (base, middle and apex) of the left ventricle with five locations examined in the base region (two covering the anterior area, one covering the lateral area, and two covering the posterior area), four locations examined in the middle region (two covering the anterior area, one covering the lateral area, and one covering the posterior area), three locations examined in the apex region (one covering the area adjacent to anterior, one covering the apex tip, and one covering the area adjacent to posterior). Elastin fiber signals were generated by autofluorescence of elastin under CY3 channel (Ex = 543 nm). Abundant elastin signals were detected in the epicardial layer (C), the endocardial layer (F), and the region associated with blood vessels (E). There was no detectable elastin signal in the acellular, collagen-dominated myocardial layer (D).