Fig. 3

Muscle biopsy from the vastus lateralis muscle in case II:2 at age 55 years. A The majority of muscle fibers are larger than normal and many of them show internal nuclei. There are also scattered small and very small fibers, and fatty replacement of muscle fibers (H&E). B The internal structure of the large fibers is slightly disturbed (NADH-TR). C Scattered regenerating fibers (arrow) (Immunostaining of embryonic MyHC). D-F Immunostaining of MyHC isoforms and perlecan. For normal control, see F. D There is nearly type 1 fiber (blue) uniformity with a few scattered very small type 2A fibers (green, arrows). There are no type 2B fibers. E High magnification shows numerous extremely small type 2A fibers (arrows). F Control muscle from a child without muscle disease demonstrating a normal mosaic pattern of three different fiber types: Type 1 fibers with slow/beta cardiac MyHC: blue, type 2A fibers with MyHC IIa: green, type 2B fibers with MyHC IIx: red and perlecan for basement membranes: yellow