Nerve Fiber Analysis and Aging Process of the Human Oculomotor Nerve

Abstract

Myelinated nerve fibers of the human oculomotor nerve were analyzed with a new staining method that permits simultaneous observation of the axon and surrounding myelin sheath. The folowing equipment was employed for the measurements: an image-analyzing digitizer, a microscope equipped with a drawing tube (or camera lucida), and a computer for data storage and statistical analysis. The numbers, transverse areas, and circularity ratios of axons were measured in 20 human oculomotor nerves. The average number of axons in an oculomotor nerve was 18, 329, and the average area of aoxns was 6.43 μm2. The number of axons decreased with age, although the average transverse area of axons did not change. The aging process might differ depending on the nerve.