The optic nerve of the mallard duck: fiber-diameter frequency distribution and physiological properties.

Abstract

AbstractA correlative study of the anatomy and physiology of the axons of the optic nerve of the Mallard duck was carried out. The principal findings were: Electronmicroscopy used in conjunction with phase contrast microscopy showed the nerve to have a fiber spectrum ranging from 0.3 μ to 6.0 μ with a mode at 1.15 μ. No unmyelinated axons were found. The cross‐sectional area of the nerve was estimated to be 4.38 mm2; assuming a mean fiber density of 350,000 fibers/mm2, the total number of axons in the nerve was estimated to be about 1,500,000. The conduction velocities of the fibers were found to range from 21 m/sec to about 3 m/sec. Different recovery cycles were found for each of the different compound action potentials. Using a graphical method, a good correlation could be established between the fiber‐size spectrum and the configuration of the compound action potential.