Figure 6.

Combined electron and light microscopy to determine the accuracy of synapse detection by array tomography. (A–C) Transmission EM (A) and light microscopy (B) images from the same section of tissue, and the two images superimposed (C). Yellow contours in all three images show mitochondria that are used as fiducial markers for aligning images. Arrowheads indicate predicted TC synapses based on the light microscopic image, colors of arrowheads show true-false evaluation based on the EM image (as depicted in (D). (C1–C5) Close up images of TC synapses predicted by light microscopy. (D) Correlative light (D1–D3) and EM (D4–D6) images from the same serial sections. Red indicates thalamic axons, green postsynaptic structure, blue synaptophysin. Black dots in EM images are gold particles from immunogold staining for GFP. Red arrows indicate the PSD from the EM images used to identify. (E) Schematics of synapse assignments based on combined EM and light microscopy. (F) Quantitation of different synapse assignments based on combined EM and light microscopy (evaluation of 322 putative TC synapses). Scale bars = 1 μm.