Fig. 3
From: Fusion of myofibre branches is a physiological feature of healthy human skeletal muscle regeneration
Confocal microscope images of 3 regenerating healthy human muscle fibres, 30 days post injury. A–F are stained for desmin (red), nestin (green), and nuclei (blue) and G–H are stained for actin (phalloidin, red), nestin (green) and nuclei (blue). A Maximum intensity projection of a 14-slice z-stack (100-μm scale bar), displaying a nestin + branch attached to a regenerating myofibre (the lower myofibre displayed here alongside an (upper) uninjured myofibre). B Maximum intensity projection of a 25-slice z-stack (20-μm scale bar). Note the striated and nestin + segment (arrows) tightly associated with the parent myofibre. This branch displays a gradual increase in nestin immunoreactivity from the point of branching (or fusion) towards its end (C orthogonal slices 7–8). D–E Maximum intensity projections of a 10-slice z-stack (20-μm scale bar). Note the small nestin + desmin + myofibre segment (arrows) nestled against the parent myofibre (nestin-desmin +). Note the approximately 10 juxtaposed myonuclei in D. G Three slices of a z-stack (scale bar, 50 μm), showing 2 myofibres. The presence of nestin at the perimeter of the upper myofibre in this image indicates ongoing regeneration, in contrast to the lower myofibre. Arrows point to a region of the regenerating myofibre that appears to be split for a length of approximately 100 μm, demarcated by nestin (H). It can be seen from the striated actin staining that the smaller segment is longitudinally continuous with the parent myofibre. *Central myonuclei potentially indicate the site of recent fusion. The position of the YZ orthogonal view images in C (20-μm scale bar), F (scale bar 5 μm) and H (scale bar 10 μm) is designated by dashed lines in B, E and G, respectively