Fig. 2

Analysis of synaptic structure using consecutive SBFSEM sections. Representative images of symmetric (a) and asymmetric (b) synapses. Symmetric synapses have similar width of pre- and postsynaptic densities associated with the synaptic junction. Asymmetric synapses have a thicker postsynaptic density compared to the presynaptic density. Black arrows indicate pre- and postsynaptic densities. Red arrows indicate synapses. SV, synaptic vesicles located in axons next to presynaptic densities. M, axonal mitochondrion. Scale bar, 160 nm (a) and 140 nm (b). (c) Representative serial sections of an asymmetric synapse with the visibly thick postsynaptic density highlighted in green. Red asterisk, axonal mitochondrion; yellow hashtag, dendritic mitochondrion. Scale bar, 400 nm.