Fig. 5.

Innervation of control muscles by host axons is stable over time. Stability of heterochronic NMJs on transplanted wild-type muscle fibers viewed in vivo over 5 d are shown. A, On day 0, host presynaptic nerve terminals (labeled with the vital mitochondrial dye 4-di-2-Asp,green) innervating grafted muscle fibers overlie postsynaptic AChR clusters (labeled with TRITC-BTX,red). Presynaptic nerve terminals overlie areas of AChR clusters with precise correspondence (the red andgreen pseudocolors of the AChRs and nerve terminals combine to give yellow). B, Five days later, the presynaptic and postsynaptic components of the NMJ still retained their close association and are unchanged from day 0. Scale bar, 25 μm.