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. 2018 Mar 19;12:5. doi: 10.3389/fnsys.2018.00005

Figure 6.

Figure 6

Ultrastructure of VUM-neuron terminals in larval (A,B) and adult fruit flies, Drosophila melanogaster (C,D). (A) Arrangement of two terminals on the surface of a larval body-wall muscle: one synaptic terminal (t1) with clear vesicles (cv) has an “electron dense T-bar” (arrow) indicating the active zone, contacts with thin sarcoplasmatic processes (SP) and, thus, corresponds to the NMJ (or type I-terminal); the other type (t2) includes dense-core vesicles (dcv) with anti-octopamine Immuno-Gold labels, 10 nm, and corresponds to type II terminals. Other abbreviations: Glial cell (GC) with nucleus; OT, octopaminergic type II terminal (Scale = 1 μm). The immunogold labels are clearly depicted in (B) (arrows) which is a higher magnification of a part of the type II terminal shown in (A). Abbreviation: ex, extracellular matrix; Ω, omega-profile on membrane of release-site. (C) shows a dense core vesicle in the process of exocytosis (arrow, see accumulated gold particles) and gold particles in the synaptic cleft (arrowheads). (D) An octopaminergic type II axon terminal with many dense-core-vesicles (dcv) on an adult Drosophila dorsal longitudinal FM labeled by 12 nm Immunogold-gold particles (arrows). The terminal makes desmosome-like contacts (arrowheads) with SP. Other abbreviation: body cavity (BC) (Scale =1 μm). (E) A higher magnification of anti-OT-immunogold labeling in the dense core vesicles and the release site (arrowhead) (Scale = 1 μm). This tissue was not contrasted by heavy metals to reveal 15 nm-Immuno-Gold labels.