Fig. 3. Representative images taken from histological sections of soleus muscle obtained at 4 weeks of age from rats injected with (A,B) saline, (C,D) neurotrophin 4/5 (NT-4/5) and (E,F) TrkB–IgG. Each section was double-stained with monoclonal antibodies A4.840 (I/b) and MY-32 (fast and neonatal). The A4.840-immunopositive fibers were visualized with a fluorescein isothiocyanate (FITC)-conjugated secondary antibody (A,C,E), and the MY-32-immunopositive fibers were visualized with a Texas Red^®-conjugated streptavidin secondary antibody (B,D,F). Asterisks mark double-stained fibers. Scale bar, 50 µm.