Confocal Microendoscopy of Neuromuscular Synapses in Living Mice

Here we describe a step-by-step method for vital imaging of neuromuscular junctions (NMJ) and axons using fiber-optic confocal microendoscopy (CME). A commercially available system, the Cellvizio Lab, can be applied to transgenic mouse lines expressing yellow fluorescent protein in all or pseudorandom sub-subsets of motor neurons. Microscopic imaging in vivo is achieved by means of a flexible optical fiber probe that excites and collects the emitted light from fluorescently labeled structures. The hand-held probe is introduced through small skin incisions to visualize nerves and neuromuscular junctions from superficial muscles. Interpolation software then reconstructs the images in real time. The images are of sufficient quality to permit screening of axonal and neuromuscular synaptic integrity and other aspects of their phenotype in live animals. Curr. Protoc. Mouse Biol. 2:1-8 © 2012 by John Wiley & Sons, Inc.