Axon numbers and distribution, myelin thickness, and the reconstruction of the compound action potential in the optic nerve of the teleost: Eugerres plumieri

The optic nerve of Eugerres plumieri contains about 200,000 fibers. Only 2.5% are non‐myelinated and the majority of these are grouped into a single tract. The axon diameters of the myelinated fibres range between 0.2 μ and 7.6 μ (mode, 0.7 μ) and the external fibre diameters range between 0.26 μ and 9.2 μ (mode, 1.0 μ). The relationship between myelin thickness, t, and axon diameter, d, shows a mode at about 0.25 (d/D = 0.67) but the distribution is wide and skewed positively. The compound action potential can be reconstructed arithmetically from morphological data and correlates well with electrophysiological recordings.