Targeted areas for data collection of axon branches and representative snapshots of cryo-ET. (A) Selection of areas for collection of tomograms. Left: Parts of cryo-EM map of grid with hippocampal neurons, selected area of interest in red and green. Middle: Low-magnification montages of areas depicted on grid map. Black arrow, branch region; white arrowhead, cell body. Right: Magnified area containing axon branch. (B–G) Slices from axon tomograms: mature branches from hippocampal (B) and thalamus (C) neurons; premature branches from hippocampal (D) and thalamus (E) neurons. Axon shafts from hippocampal (F) and thalamus (G) neurons. Scale bars: 100 µm (A left); 1.5 µm (A center and right); 250 nm (B–G).