Voxel gray-scale values for the narrow regions of membrane between the connection sites of nubs and connection sites of their paired AZM/non-AZM macromolecules and for the rest of the membrane of eight synaptic vesicles.

Nv, number of voxels; Avg±SD, average gray-scale value (ranging from 0, black, to 1000, white) ± Standard Deviation (SD). Average gray-scale values for the regions between nubs and AZM/non-AZM macromolecules per vesicle are significantly lower (darker) than for the rest of its membrane, except for one value (asterisk), as determined by ANOVA analysis with Tukey Post Hoc test (p