Figure 1.

Identification, segmentation, and extraction of the SAS of a synaptic junction from serial images obtained with combined FIB/SEM. A–D, Sections 91, 94, 98, and 101 from a stack of serial sections obtained with FIB/SEM from the rat somatosensory cortex. Identification of an AS whose prominent PSD is clearly visible (arrow). Note that the identification was not based on single images but on the examination of the full sequence of images where the synapse was visible (numbers in the top-right corner of each frame correspond to section number; each individual section was 20 nm thick). E–H, Segmentation of the synaptic junction (green) with EspINA software. I, J, The resulting 3D object representing the synaptic junction (green) visualized from two different angles. K, L, The SAS (yellow) that has been extracted from the 3D synaptic junction shown in I, J. M, Panoramic view of all the SAS extracted from a whole stack of images. Scale bar: 1 µm (A–H).