Fig. 1: Axons are pearled, not tubular, under homeostatic conditions.
From: Membrane mechanics dictate axonal pearls-on-a-string morphology and function
a, Representative electron micrographs from acutely extracted mouse brain tissue (left), organotypic slice cultures of mouse hippocampus (middle) and dissociated mouse hippocampal neuronal culture after high-pressure freezing. Some axons in each micrograph are traced and color coded on the bottom; scale bars, 500 nm. b, High-magnification images of axons representative of each condition. More example micrographs are found in Extended Data Fig. 1a,b,e; scale bars, 200 nm. c, A schematic showing two NSVs flanked by a connector. Inflection points define the boundary between these two features. Both width and length are measured at NSVs and connectors, as shown. d, Plots showing dimensions of NSVs (left) and connectors (right) from indicated tissue types. Dimensions are measured from three independent samples for acutely extracted brain tissue and dissociated neuron culture and one for organotypic slices; n = 30 axons from each acutely extracted sample, n = 133 axons from the organotypic sample, and n = 100 axons from each dissociated sample. Super plots showing variability are available in Extended Data Fig. 1f. Data are shown as mean ± s.e.m. and were analyzed by Kruskal–Wallis test, followed by a Dunn’s multiple comparison test. e, Representative STED micrographs showing axons from organotypic slice cultures of mouse hippocampi. The numbers represent the length of each NSV, measured at full-width half-maximum (FWHM) using MATLAB scripts. Numbers indicate the measured length at each NSV; scale bars, 200 nm; AU, arbitrary units.
