Fig. 3

Histological staining and analysis of fiber size, fiber number and fiber type in M. soleus. a Hematoxylin and eosin-stained transverse cryosections of WT and Hom mice. The sections of the Hom mice show increased fibrosis (asterisk), several fibers with central nuclei (black arrowheads), and very small fibers (arrows) and degenerating fibers in the aged Hom mice (white arrowheads), indicating an increased myopathic phenotype in these animals. b Statistical evaluation of respective percentages of fibers with centrally located nuclei using Kruskal-Wallis test and chi-squared independence tests. The number of muscle fibers with centrally located nuclei is significantly increased in adult and aged Hom animals (adult: n = 6; p = 0.0033; aged: n = 6, p < 0.0001). c The total number of fibers is significantly lower in the soleus muscle of Hom animals (adult: n = 6; p = 0.0152; aged: n = 6, p = 0.0317). d-e When compared to WT mice, the mean minimal diameter of type I fibers is significantly larger in adult Hom animals (****p < 0.0001), whereas they are smaller in aged mice (****p < 0.0001), indicating that in Hom mice type I fibers don’t increase their size as much as in WT animals during aging. f-g When compared to WT mice, the mean minimal diameter of type II fibers is significantly larger in adult and aged Hom animals (****p < 0.0001, **p = 0.0061)