Table 1.

Diameter of microtubules and neurofilaments in axons, and intermediate filaments (microfilaments) in astrocytes

Structure	Mean diameter (nm) ± SD n = 17
Microtubules within axons	25.70 ± 5.93
Neurofilaments within axons	12.18 ± 1.75
Intermediate filaments within astrocytes	11.67 ± 5.21

The differentiation between axons and astrocytes was based on the presence of microtubules and neurofilaments within axons and intermediate filaments within astrocytes. Measurements were performed on ultrathin longitudinal sections of rat optic nerves using electron microscope imaging.