neflbE4 and neflbE3 distribution within motor neurons. (A) (i,ii), in vivo observation of single motor neurons expressing eGFP-neflbE4. Motor neurons expressing eGFP-neflb4E extend long and ramified axons. (a–c), eGFP-neflbE4 is particularly abundant in the specific area representing the axonal branching (white dotted circles) and NMJ buttons (white arrows). (B) (i,ii), single motor neurons expressing eGFP-neflb3E. eGFP-neflbE3 mostly aggregated or assembled into a long, massive, unramified bundle. (a–c), eGFP-neflbE3 was reduced or absent in the axonal ramification sites and NMJ buttons.