Cryo-electron tomography of axons and varicosities in cultured primary mouse dorsal root ganglion neurons (Glacios 200 kV comparative subset, 6-7 February 2025)

Cryo-electron tomography of intact, unmilled peripheral axons and their varicosities in primary dorsal root ganglion neurons dissociated from 3-month-old mice and cultured for 48 h on gold Quantifoil grids. The axons grow thin enough over the grid surface to be imaged directly, with no cryo-sectioning and no focused-ion-beam milling, so the varicosities (roughly 0.6-1.9 microns across) and the much narrower shafts connecting them are captured in a near-native state. Tilt series were collected from -51 to +51 degrees in 3 degree increments on a Glacios operated at 200 kV, equipped with a Selectris energy filter and a Falcon 4i direct electron detector. Tomograms were reconstructed by weighted back-projection in IMOD and denoised by IsoNet deconvolution. This dataset holds 20 tomograms, all of which carry a manually curated multi-class organelle segmentation covering the plasma membrane, microtubules, mitochondrial outer and inner membranes, endoplasmic reticulum and vesicles enclosed within it, multivesicular bodies, multilamellar vesicles, endosomes, phagophores and free cytoplasmic vesicles. The study uses these to ask how the spatial confinement of an axon constrains organelle architecture.