Unmyelinated Nerve Fiber Analysis of the Human Abducent Nerve

Abstract

Summary: Unmyelinated nerve fibers of the abducent nerve have occasionally been observed with electron microscopes, but, to our knowledge, they have never been evaluated from the morphometric point of view. We analyzed the aging process of the unmyelinated nerve fibers in the human abducent nerve with the help of a new staining method suitable for morphometric research on the nervous system. We studied numbers and transverse areas of unmyelinated fibers of the abducent nerve in 10 cadavers. Our findings were that (1) these fibers were distributed diffusely, (2) their number decreased with age, and (3) the mean transverse area did not change with age. Most of the unmyelinated axons were thinner than the myelinated axons. These results may be important for analysis of clinical signs in relation to aging and ophthalmologic functions.

Morphological Differentiation of Nerve Fibers: Central, Peripheral, Myelinated and Unmyelinated

“…The shrinkage ratios during the preparation of histology sections amounted to 10 + 0% in length according to our researches2-4, [6][7][8]11,12,[15][16][17][18][19][20][21].…”

“…Up to now, however, no staining method was available for unmyelinated nerve fibers, except for transmission electron microscopy. Reports on the evaluation of nerve fibers1-21) are rather limited in numbers except for our contri-butions2-4, [6][7][8]11,12,[15][16][17][18][19][20][21].The purpose of this paper is to introduce two discriminative staining methods with discussion on the modifications required in order to differentiate the various types of nerve fibers described above. These methods not only differentiate various nerve fibers, but also produce good results from the view point of morphometry.…”

Unmyelinated Nerve Fiber Analysis of the Human Oculomotor Nerve

“…The methods for fixation, embedding, sectioning, staining and measurement were the same as in our previous reports2, 3,6,7,[9][10][11]14,15). For morphometric measurements, we employed the systemic sampling method.…”

Morphometric evaluations of the human nervous system

“…Unmyelinated nerve fibers of the abducent nerve had occasionally been observed with electron microscopy, but they had never been evaluated from the morphometric point of view. Numbers and transverse areas of unmyelinated fibers of the abducent nerves from 10 cadavers aged 63–88 (average 74.7) years were evaluated using the same methods 63 . The results show (i) that unmyelinated fibers are distributed diffusely; (ii) that their number decreases with age; and (iii) that the mean transverse area does not change with age.…”