Figure 2

Syp-EGFP⁺ synaptic vesicles localize at sites of oligodendrocyte process interaction. (A) Representative confocal images of TdTomato-CaaX-labeled reticulospinal axons and EGFP-labeled synaptic vesicles in 4 dpf zebrafish spinal cord. Note Syp-EGFP puncta at both axon varicosities (yellow arrowheads) and intervening segments (red arrowheads). (B) Graph displays the proportion of axonal regions of interest (ROIs) that contained Syp-EGFP puncta. Each point represents the proportion of ROIs containing EGFP puncta per individual reticulospinal axon analyzed. Sample size = (number of ROIs, number of axons, number of animals) 339, 9, 8; bars show mean ± SEM, paired t-test. (C) Syp-EGFP and mRFP-labeled oligodendrocyte membranes observed in the larval zebrafish spinal cord (4 dpf). Arrowheads point to Syp-EGFP puncta associated with mRFP-labeled oligodendrocyte process extensions. (D) Graph displays the percent coverage of vesicle-enriched axon segments and intervening axon segments by oligodendrocyte process extensions. Sample size = (number of axons, number of animals) 9, 9; bars show mean ± SEM, unpaired t-test. For (A) and (C), images are lateral view with anterior left and dorsal up; scale bars = 2 μm.