Fig 1: Histology of the vastus lateralis muscle from a 6-month-old DE50-MD dog. (A-E) Immunohistochemistry of a section of vastus lateralis muscle showing (A) CCL2 (magenta), (B) CD18 (green) and (C) a merged image of CCL2, CD18 and Hoechst 33342 (blue), with magnified views of the boxed region in C shown for (D) CCL2 and (E) CD18 staining. (F-J) Immunohistochemistry of a serial section showing (F) CCL2 (magenta), (G) MAC387+ regions (green) and (H) a merged image of CCL2, MAC387 and Hoechst 33342 (blue), with magnified views of the boxed region in H shown for (I) CCL2 and (J) CD18 staining. (K) A serial section with H&E staining showing cell infiltrate within and between muscle fibres, fibres with internalised nuclei and hypercontracted fibres (darker magenta). (L) Serial section with acid phosphatase (AP) staining showing positive red staining at areas of cell infiltrate and within some muscle fibres. (M-O) Serial section of immunohistochemistry with no primary antibody as a control with magnified views of the region of inflammation (dashed box) shown for the (N) magenta (CCL2) and (O) green (CD18/MAC387) channels. Scale bar: 100 µm.