Med. Weter. 68 (6), 371-375, 2012

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Wawrzyniak-Gacek A., Jaworska-Adamu J.
Ultrastructural changes in the oligodendrocytes in the central gray matter of the old rats
The structure and functions of the oligodendrocytes in different areas of the brain in the normal process of aging in mammals is poorly known. The purpose of this study was to investigate three types of oligodendrocytes, their ultrastructure as well as morphology of myelin sheaths of nerve fibers in the central gray matter (substantia grisea centralis-SGC). The study was conducted on adult rats, 25-week-old and140-week-old rats. The animals were perfused with fixative through the left ventricle and the midbrain containing SGC were collected. Ultrathin sections were observed and photographed in an electron microscope. In both tested age groups oligodendrocytes were usually arranged in pairs. In adult rats, the SGC survey revealed a clear advantage and medium oligodenrocytów, and, rarely, dark cells with normal ultrastructure. In old rats, oligodendrocytes were dominated by medium and dark cytoplasm and less commonly with clear cells. The cytoplasm of the few bright and medi-um oligodendrocytes expressed the morphological changes manifested by the presence of varying electron densities and size of inclusions and the insulation of nerve fibers were also changed. The presence of the few bright oligodendrocytes in the SGC in old rats suggests that a few of their young forms of progenitor cells may arise, as in other areas of the brain normally aging in mammals. These new cells may participate in remielinization nerve fibers affecting the proper connections SGC with other brain areas.
Keywords: oligodendrocytes, nerve fibers, central gray matter, old rats