Molecular anatomy of axon retraction. A, B, Images of WT (+/+) (A) and stathmin mutant (stai^B200/ stathmin^L27) (B) muscle 4 NMJs immunostained with the various antibodies shown. Arrowheads denote empty terminal patches of HRP that are indicative of boutons in the process of retraction. Scale bars: 10 μm. C, A model of the sequential stages of axon retraction separating the process into periods of preretraction, early retraction, and late retraction and the changes observed in various synaptic proteins during those periods.