Figure 5.

Scanned slides depicting cut sections of fixed Müller muscles stained with methylene blue. (A) Cross-section of a nerve bundle between muscle fibers. (B, C) Cross-sections of myelinated nerves with larger diameters (B, 16.92 µm, C, 15.38 µm). As highlighted by the stain, individual axons are encased in myelin. The arrows indicate axons of various sizes (yellow = smaller diameter and orange = larger diameter). In cases of seemingly elongated fibers, which may represent oblique cuts of circular axon profiles, the diameter measurement was performed over the shortest axis rather than the long one; using this rule, the true diameter was obtained. Overall, 580 usable axons were located and measured, with an average diameter of 5.37 micrometers (standard deviation = 2.89).