Skip to main content
. 2018 Sep 13;12:72. doi: 10.3389/fnana.2018.00072

FIGURE 5.

FIGURE 5

Vesicles and their macromolecular connections at and near the extra-active zone region of the presynaptic membrane. (A) 4 nm thick virtual slice showing some SVs and one DCV near the extra-active zone region (white dashed lines) of the presynaptic membrane. One SV (∗) is in contact with this region of membrane. Two SVs are in contact with the active zone portions of the presynaptic membrane (red dashed lines). Scale bar = 50 nm. (B) Surface models (color coded as in Figures 1, 3) generated from 15 serial virtual slices [the same SV in contact with the presynaptic membrane in (A) is also indicated by (∗)] reveal many more SVs near the extra-active zone region of the presynaptic membrane than evident in (A). Non-AZM macromolecules connected to the cytosolic surface of these vesicles link the vesicles to the presynaptic membrane and to other vesicles or they appear to end blindly in the cytosol. The docked SVs are also linked to components of the AZM. The mast is connected to an undocked vesicle by a topmast (light green) as described and discussed in Szule et al. (2012); we also noted topmasts extending from other masts shown in this study connected to SVs and DCVs, but we did not include them in the other surface models presented here. The muscle was fixed with an aqueous solution of glutaraldehyde and stained with aqueous solutions of osmium tetroxide and uranyl acetate.