Figure 3
From: Low survival rate and muscle fiber-dependent aging effects in the McArdle disease mouse model
Age-dependent increase of IIa and IIx fibers atrophy. (A) Fiber type stains for myosin heavy chain (MHC) I, IIa, IIx, and IIb as overlapping double stains in soleus muscle from McArdle (McA) mice demonstrate that type I fibers are not affected structurally by glycogen accumulation in any of the ages analyzed, whereas type IIa, IIa/IIx mixed, and IIx fibers present an age-dependent increase in atrophy. All scale bars correspond to 150 µm. (B) MHC double stain in tibialis anterior (TA) muscle shows atrophy in IIa, IIx and mixed IIa/IIx fibers in 8-week-old McArdle (McA) mice, which is further exacerbated in 70-week-old McA mice. Mixed IIx/IIb fibers seems to be protected from atrophy. Longitudinal sections are also shown. (C) Consecutive soleus sections from 35-week-old McA mice stained for I/IIa and II/IIx fibers showing almost intact type I fibers but highly degenerated IIa, IIx and IIa/IIx fibers. Scale bars correspond to 150 µm. All scale bars correspond to 150 µm, while in longitudinal sections the scale bars correspond to 75 µm. (D) Two consecutive sections of TA muscle from 70 wo McA mice stained for IIx/IIb fibers and fibronectin shows the presence of fibrosis in muscle regions enriched in IIx fibers and its absence in IIx/IIb enriched sections. In (A–D) DAPI was used to stain cell nuclei.
