The figure presents comparative ultrastructural and quantitative analyses of axonal morphology between control and experimental groups. Panels A–F show high-resolution electron microscopy images of myelinated axons across three anatomical regions: optic nerve (ON), lumbar spinal cord (LSCC), and thoracic spinal cord (TCSC). Control samples (A, C, E) display axons with circular profiles and uniform myelin sheaths, while experimental samples (B, D, F) exhibit variability in axon diameter and sheath thickness. Images highlight cross-sectional differences in fiber density, packing, and myelin compaction. Panels G–I provide scatter plots of axon diameter measurements, with regression lines indicating distribution relationships between conditions. Each scatter plot plots individual axon diameters (µm) against frequency counts, showing that experimental groups tend toward altered size distributions relative to controls. Panels J–L present histograms of axon diameter frequency distributions for ON, LSCC, and TCSC, respectively, with distinct peaks indicating shifts in axonal populations between groups. Panels M and N summarize quantitative comparisons in bar graph format: panel M shows mean axon diameter differences in the optic nerve, while panel N compares diameters across spinal cord regions. Statistical indicators (asterisks) denote levels of significance, with *** representing p < 0.001 and ** representing p < 0.01. The collective dataset illustrates region-specific and statistically significant differences in axon diameters between control and experimental conditions, integrating structural micrographs with quantitative morphometric analysis.