Comparison of Morphometric Aspects of Light and Electron Microscopy of the Hypoglossal Nerve between Young and Aged Male Wistar Rats

(Pages: 229-236)
Nabiollah Soltanpour, Ph.D., *Yasser Asghari Vostacolaee, M.D., Mohsen Pourghasem, Ph.D.,
* Corresponding Address: P.O.Box: 47176 47745 Department of Anatomy Biology and Molecular Research Center Babol University of Medical Sciences Babol Iran Email: drnsoltanpour@yahoo.com
Any use, distribution, reproduction or abstract of this publication in any medium, with the exception of commercial purposes, is permitted provided the original work is properly cited This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Soltanpour Nabiollah, Asghari Vostacolaee Yasser, Pourghasem Mohsen. Comparison of Morphometric Aspects of Light and Electron Microscopy of the Hypoglossal Nerve between Young and Aged Male Wistar Rats. Cell J. 2012; 13(4): 229-236.

Abstract

Objective:

Age-related changes occur in many different systems of the body. Many elderly people show dysphagia and dysphonia. This research was conducted to evaluate quantitatively the morphometrical changes of the hypoglossal nerve resulting from the aging process in young and aged rats.

Materials and Methods:

Through an experimental study ten male wistar rats (4 months: 5 rats, 24 months: 5 rats) were selected randomly from a colony of wistars in the UWC. After a fixation process and preparation of samples of the cervical portion of the hypoglossal nerve of these rats, light and electron microscopic imaging were performed. These images were evaluated according to the numbers and size of myelinated nerve fibers, nucleoli of Schwann cells, myelin sheath thickness, axon diameter, and g ratio. All data were analyzed by Mann-Whitney, a non-parametric statistical test.

Results:

In light microscope, numbers of myelinated nerve fibers, the mean entire nerve perimeters, the mean entire nerve areas and the mean entire nerve diameters in young and aged rats' were not significantly different between the two groups.

In electron microscope, numbers of myelinated axons, numbers of Schwann cell nucleoli and the mean g ratios of myelinated axon to Schwann cell in young and aged rats were not significantly different. The myelinated fiber diameters, the myelin sheath thicknesses, myelinated axon diameters and the mean g ratio of axon diameter to myelinated fiber diameter in young and aged fibers were significantly different

Conclusion:

The mean g ratio of myelinated nerve fibers of peripheral nerves stabilizes at the level of 0.6 after maturation and persists without major change during adulthood. This ratio of axon diameter to fiber diameter (0.6) is optimum for normal conduction velocity of neural impulses. Our study indicated that the g ratio of myelinated nerve fiber of the hypoglossal nerve decreased prominently in aged rats and can be a cause of impairment in nerve function in old age. Thus, prospective studies concerning electrophysiological and conductive properties of the peripheral nerve could be useful to clarify further the effects of aging on peripheral nerves.