An Integrated Micro- and Macroarchitectural Analysis of the Drosophila Brain by Computer-Assisted Serial Section Electron Microscopy
Figure 6
Correlation between spatial overlap of neurite segments and probability of synaptic contacts in VNC microvolume.
Panels A–D show 3D digital models of elements of VNC microvolume (frontal view). All dendritiform neurites are rendered in transparent shades of yellow-brown. In panel A, one axiform neurite (a) and two dendritiform neurites (d1, d2) are rendered in solid colors. Red frames delineate boundaries of envelope surrounding the three profiles. In this example, envelope of d1 and a overlap slightly (less than 10% of volume of envelope of a is shared with envelope of d1); envelope of d2 and a overlap strongly (greater than 50% of volume of envelope of a is shared with envelope of d2). In each one of panels B–D, one varicose neurite (a) is rendered in solid green or blue; the postsynaptic dendritiform neurites that actually form synaptic contacts with the varicose neurite are rendered in solid colors (yellow-brown). Note tight clustering of denritiform neurites around the corresponding varicose element. (E) Histogram depicting correlation between overlap of pre- and postsynaptic elements (x-axis) and frequency of synaptic contacts (y-axis). Counted for the VNC microvolume; overall number of presynaptic elements over 1 µm length: 40; postsynaptic elements: 105. For example, only 17% of the pre- and postsynaptic elements whose envelopes overlap less than 10% actually form synaptic contacts.