Fig. 4: RGC axon diameters increase with intraretinal axonal length.

All results were obtained from a single donor. a, RGC axon sampling locations (lowercase letters a, b, c₁, c₂) overlaid with model axonal trajectories. Red triangle, fovea; blue triangle, optic disc. b, Top: cropped region from a TEM image of a cross-section of RNFL axons. Middle: a magnified view of the TEM image (left) and corresponding segmentation (right; colors indicate different axons). Bottom: outlines of segmented axons; black line indicates the minor axis of an ellipse fit to one axon outline. The image shown is from one of four sampling locations in a single human retina and is representative of the segmentation and analysis performed at all four locations. c, Histograms of RGC axon diameters at four different locations sampled from one human retina. Model axonal length for the four locations marked on the left of each histogram. The numbers indicate the number of estimated RGC axon diameters per location; black lines, fit of Gaussian mixture model with two components; black dots, mean value of each component (μ₁ and μ₂). d, Mean ± s.d. of the two Gaussian components fit in c versus model axonal length (Extended Data Fig. 7d–g). Means and s.d. obtained by fitting Gaussian mixture models to the distributions shown in c.

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