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Figure 3 (A, B) Higher power view of the boxed area in Figure 2A. Picrosirius red-stained sections of collagen implanted into myocardial infarct scar area. The bright red-stained implanted collagen is in the center of the scar (A, B; black arrows), and the scar is divided into endocardial and epicardial portions (A: x40; B: x100). (C) Higher power view (x400) of Figure 3B show the border (black arrows) between the collagen implant (left side) and the native collagen deposition (right side). The collagen implant is homogeneous. There is no bundle formation as in native collagen deposition. (D) Picrosirius red staining of in vitro collagen for implantation. The collagen staining is bright red and homogeneous, similar to that shown in Figure 3C (collagen-treated) (x400). (E, F) Higher power view of the boxed area in Figure 2B. Picrosirius red-stained sections of a six-week-old saline-treated myocardial infarct scar area. Red staining shows the collagen deposition, whereas yellow shows the viable myocardium in the scar, and the blue staining shows the blood vessels (E: x40; F: x100). In contrast, note that no blue dye is found in the implanted collagen area in Figures 3A and 3B, and collagen deposition is much more intense in Figures 3A and 3B (collagen-treated) compared with Figures 3E and 3F (saline-treated).