Side differences of the age-related changes in the white matter and the myelinated nerve fibers in the white matter of female rats

Abstract

The present study tested if there were side differences of the white matter and the myelinated fibers in the white matter of female rats, and if there were side differences in the age-related changes of the white matter and the myelinated fibers in the white matter of female rats. Five young, five middle-aged and five aged female Long-Evans rats were quantitatively investigated using electron microscopic technique and stereological methods. We found no side differences of the white matter volume, the total volume, total length and mean diameter of the myelinated fibers in the white matter of young, middle-aged, and aged female rats. When compared to middle-aged female rats, the total length of the myelinated fibers in the white matter of the left hemisphere in aged female rats was decreased significantly, but the total length of the myelinated fibers in the white matter of the right hemisphere in aged female rats was non-significantly decreased. Our data indicated that there were no significant side differences in the white matter and the myelinated fibers in the white matter in young, middle-aged, and aged female rats. However, we demonstrated that the aged-related changes of the myelinated fibers in the white matter of the left hemisphere and right hemisphere were different. The results obtained in the present study will provide biological basis for the understanding of the asymmetry of cerebral functions.