Figure 3.

Lamprey reticulospinal (RS) synapses and injection strategy. (A) Cross-section (1 μm thick) of a lamprey spinal cord stained with toluidine blue. Note the giant RS axons in the ventromedial tract. V—ventral; D—Dorsal. (B) Diagram of a lamprey spinal cord showing the strategy for axonal microinjection and stimulation. After microinjection of the α-synuclein dimers, the synapses within three regions of the axon were evaluated: those treated with higher concentrations of the protein (5–8 μM), lower concentrations of the protein (0.5–4 μM), or no protein (0 μM; Controls). These regions were determined based on diffusion of a co-injected fluorescent dye. (C) Diagram of an injected RS axon indicating the locations of giant RS synapses along the axonal perimeter. (D) Electron micrograph of an unstimulated, control RS synapse showing the large size of the synaptic vesicle (SV) cluster.