Figure 5. Representative cross-sections of TA muscles in 60-day-old SOD1^WT and SOD1^G93A mice that have been stained for neural cell adhesion molecule (NCAM) to identify NCAM positive, denervated muscle fibres.

In SOD1^WT mouse TA muscles (A), the fibres did not express NCAM, indicating that they were all normally innervated. In the SOD1^G93A mouse TA muscles (B), numerous muscle fibres expressed NCAM. The number of NCAM negative muscle fibres that were innervated by motor axons is summarized in Fig. 6. Representative photomicrographs of TA muscles from SOD1^WT (C) and SOD1^G93A (D) mice are immunostained with anti-MHCIIb monoclonal antibody (clone BF-F3), which labels type IIB fibres. There was considerable whole muscle and type IIB fibre atrophy of the muscles of SOD1^G93A mice compared with SOD1^WT. There was also overt loss of type IIB fibres, particularly from the superficial regions of TA muscles from SOD1^G93A mice. The scale bar in A is 100 μm; the scal bar in D is 1 mm.