中文摘要：

目的探讨雄性大鼠左右大脑半球白质及其内有髓神经纤维是否存在显著性差异，以及每侧大脑半球白质及其内有髓神经纤维的老年性改变是否一致。方法运用透射电子显微镜和体视学方法分别对5只年轻（6～8月龄）和4只老年（18月龄）雄性Long-Evans大鼠左侧、右侧大脑半球白质体积及白质内有髓神经纤维体积、长度和直径进行定量研究。结果年轻组大鼠和老年组大鼠左右大脑半球白质体积及白质内有髓神经纤维体积、长度和直径均不存在显著性差异。每侧大脑半球自质及其内有髓神经纤维总长度和总体积均随年龄增加而降低，右侧半球白质体积、右侧半球白质内有髓神经纤维总体积和左侧半球白质内有髓神经纤维总长度随年龄增长分别显著性降低32．9％、28．6％和49．3％。结论正常年轻和老年雄性Long-Evans大鼠两侧大脑半球的白质及其内有髓神经纤维均不存在显著性侧别差异。老年雄性Long—Evans大鼠右侧大脑半球白质体积、右侧大脑半球白质内有髓神经纤维的总体积和左侧大脑半球白质内有髓神经纤维总长度存在显著老年性改变。

英文摘要：

Objective To explore if there are significant differences in the white matter and the myelinated fibers between left and right hemispheres of male rats and if the age-related changes of the white matter and the myelinated fibers in the white matter are same for left hemisphere and fight hemisphere of male rats. Methods The white matter and the myelinated fibers in the white matter from 5 male young Long-Evans rats （6-8 month old） and 4 male aged Long-Evans rats （18 month old） were quantitatively investigated with the stereological techniques and transmission electronic microscope technique. Results There are no significant differences of the white matter and the mylinated nerve fibers in the white matter between the left and right hemispheres in both young and aged groups. Although the total volume of the white matter and the total length and the total volume of the myelinated nerve fibers in the white matter were reduced in both left hemisphere and right hemisphere, only the white matter volume and the total volume of the myelinated fibers in the white matter of fight hemisphere and the total length of the myelinated fibers in the white matter of left hemisphere were significantly decreased by 32.9 % , 28.6 % and 49.3 % , respectively. Conclusion There are no significant differences in the white matter and myelinated nerve fiber in the white matter between left and fight hemispheres in both young and aged male Long-Evans rats. The white matter volume and the total volume of the mylinaed fibers in the white matter of right hemisphere and the total length of the myelinated fibers in the white matter of left hemisphere in the aged male rats are significantly decreased when compared to young rats.