Supraspinatus tendons of NC and HRLF rats.

<p><i>(A)</i> A low power photo of the enthesis of a supraspinatus tendon attaching to greater tuberosity of humerus in an aged NC rat. Scale bar = 250 µm. <i>(B)</i> A higher power image of same section as shown in A. Inset is an enlargement of boxed area shown in A. <i>(C&D).</i> Photos of the enthesis of supraspinatus tendons in <i>(C)</i> an aged 12-week HRLF rat, and <i>(D)</i> a young adult 12-week HRLF rat. Arrows in C indicate increased site of cellularity, a region shown enlarged in inset. Scale bar in C is 50 µm; panels B and D are at same magnification. (E–H) Photos of distal cut ends of a supraspinatus tendon in: <i>(E)</i> an aged NC rat, <i>(F)</i> aged 12-week HRLF rat, <i>(G)</i> young adult NC rat, and <i>(H)</i> young adult 12-week HRLF rat. Arrows in F and H point out sites of increased cellularity and vascularity (cap = capillary bed). T = tendon; M = muscle fibers. Scale bar in F is 100 µm; panels E, G and H are at same magnification.