Fig. 5

Myofilament formation at the basement membrane. a. Confocal microscope image of a regenerating human muscle fibre (attached to an uninjured fibre), stained for desmin (red), macrophages (CD68, green), basement membrane (collagen IV, yellow) and nuclei (blue), 7 days post injury. The images are presented with all 4 colours merged or split into fewer channels for clarity. Note the distinct necrotic (asterisk) and regenerating (arrows) zones. Part of the fibre has become detached from the uninjured fibre and folded back on itself during the staining procedure. Note the capillaries stained with collagen IV on the surface of the fibres. Scale bar, 100 μm. The area indicated by the dashed line box was imaged at higher magnification, shown in b. b Eight to nine adjoining nuclei can be seen (red box) in a desmin dense area of this regenerating zone, indicating they are potentially newly fused myogenic cells. Macrophages were also observed within the myofibre basement membrane in this narrow zone. The dashed line indicates the location of the YZ orthogonal view. Scale bars, 20 μm