Figure 3: Size distribution of myelinated fibers (a) and respective axons (b) of the proximal segment of the right sural nerve of young (90-day-old) female Wistar rats, obtained by automatic (black circles) and semiautomated (white circles) morphometry. Note that myelinated fibers distributions are bimodal while axon distributions are unimodal. Note also that the fiber distribution obtained with the automatic method is skewed to the right in 0.5 μm while the axon distribution is skewed to the left in 0.5 μm, due to the overestimation of the myelin sheath thickness.