Figure 1

Nerve terminal bouton loss in response to an extracellular cue occurs in the absence of neuronal cell bodies. All preparations were fixed in 4% paraformaldehyde prior to immunostaining for neurofilament 165 and SV2 (green: axons and terminals), visualised with a Cy2-conjugated secondary antibody and co-stained with TRITC-αBTX (red: muscle endplates), 165 min after a 15 min BzATP pulse (100 μM). Both 'occupied' (a: arrow) and 'unoccupied' (a: arrowhead) endplates were present, as were unoccupied endplates with intact presynaptic axons (b). Many terminals appeared to be in the process of retraction resulting in minor (c: asterisk) or major (d: asterisks) regions of unoccupied endplates. These were classified as 'intermediate' in subsequent data. Control nerve/muscle preparations, which were maintained in physiological saline for up to 300 min, showed no visible signs of degeneration or retraction of nerve terminals (e). Scale bar a-e = 15 μm