Model construction. (A) Example of an SBFSEM. Rod terminals are colored in red; cone terminal is colored in blue. Rod 1 used for reconstruction is shown in brighter red. (B) Diagram of an invaginating rod synapse. Vesicles surround the synaptic ribbon. RBP dendrites are in magenta, and HC dendrites are in turquoise. Modified under a Creative Commons License from Webvision (http://webvision.med.utah.edu/). (C) Magnified image of rod 1. Postsynaptic HC dendrites are in turquoise, and RBP dendrites are in magenta. (D) Reconstructed rod 1 terminal along with HC and RBP dendrites. The synaptic ribbon (dark blue) and mitochondrion (green) are also shown. (E) Mesh structures of the same cells. (F) Illustration of four reconstructed rod spherules (rods 1–4) with two RBPs (blue and yellow). (G) Mesh structures of rods 2–4 along with the postsynaptic HC and RBP dendrites. Scale bars = 500 nm. Details of these mesh structures are provided in Table 1.