Figure 2.

Neuromuscular junctions (NMJs) in both diseased TG and KI males show no evidence of morphological denervation but are consistently fragmented. Despite notable fragmentation, pre- and postsynaptic components of the NMJ showed precise alignment between the overlying synaptophysin labelled nerve terminals and the underlying α-bungarotoxin labelled (BTX) acetylcholine receptors (A, B). In short, there was no evidence of exposed endplates indicative of denervation (B, F). NMJs of wildtype (WT) muscle showed the typical, pretzel like morphology (A), albeit junctions in the levator ani (LA) muscle used for the KI model normally look more fragmented, like a collection of grapes. Regardless, using a consistent criterion to identify and count the number of distinct postsynaptic clusters that made up the junction revealed that junctions in diseased muscle of both TG (A) and KI males (E) are markedly fragmented (white arrows point to examples of) compared to WT junctions. Nearly every NMJ in the anterior tibialis of myogenic TG males (C) was fragmented while 58% of LA junctions in KI males show fragmentation (G). Assessing the degree of fragmentation within each NMJ revealed that nearly all myogenic junctions are completely fragmented (D), while only about 20% of KI junctions show complete fragmentation. * P <  0.05 compared to WT controls. Error bars represent standard error of the mean, with n = 4 mice/group for TG and n = 5 mice/group for KI estimates of denervation and fragmentation. Twenty junctions were examined per mouse. Scale bars indicate 25 microns.