Array tomographic synapsin I immunofluorescence in the cerebral cortex of an adult YFP-H mouse is punctate and consistent with synapse identity. (A) A volume rendering of 60 serial sections (200 nm each) through the entire cortical depth, including portions of the striatum. While all subsequent experiments and analysis were performed on thinner, 70 nm sections, the thicker sections in this case have allowed us to collect a larger volume and to better visualize the extensive dendrites of pyramidal neurons. Synapsin (magenta), tubulin (blue), and YFP (green). Scale bar, 50 μm. (B) A close up of layer 5 pyramidal neurons labeled with YFP. (C–H) Zoomed-in view of layers 1 (C), 2/3 (D), 4 (E), 5a (F), 6a (G) and white matter and striatum (H). Scale bar for B–H, 10 μm. See also Movie S1 for a more revealing rendering of the same image volume and Figure S1 for comparison of different synapsin antibodies.