Figure 2.

Control and BoTx/A-treated endplates dual-labeled with rhodamine-conjugated α-bungarotoxin and FITC-conjugated secondary IgGs reactive with antibodies bound to synaptobrevin, SNAP-25, or neurofilament. On control sternomastoid muscle fibers, synaptobrevin (a) and SNAP-25 (d) staining was colocalized within the areas occupied by the nAChRs; unlike synaptobrevin, SNAP-25 was also detected in the axons. At d9, both synaptobrevin (b) and SNAP-25 (e) were detected in the sprouts extending beyond the area containing nAChRs (arrows). By d28, sprouts containing the v-SNARE (c) and t-SNARE (f) had extended to form a complicated network. (c and f, arrowheads) At this time, clusters of nAChRs were detected abutting these sprouts. (g) This clustering of nAChRs was also seen in mouse LAL injected with BoTx/A 18 days earlier and dual-stained with antineurofilament IgG. (Bars = 20 μm.)