论文部分内容阅读
目的阐述如何应用新体视学方法研究大鼠白质无髓神经纤维的老年性改变,以便弄清楚导致老年白质有髓神经纤维总长度缩短的确切原因。方法本实验用10只6~8月龄Long-Ev-ans大鼠和8只18月龄以上同种大鼠。应用电镜技术及相应的体视学方法计算白质内无髓神经纤维的体积密度、长度密度和白质内无髓神经纤维的总体积、总长度。结果本研究发现雄性和雌性大鼠大脑白质无髓神经纤维总长度均无显著性老年性缩短;白质内无髓神经纤维总体积其雌性组和综合性别组均存在显著性的老年性降低;雄性大鼠无髓神经纤维总体积老年性降低虽然没有显著性,但是降低高达31%。结论老年大脑白质存在着大直径无髓神经纤维的显著性丢失,同时存在细小直径的有髓神经纤维脱髓鞘改变,在一定程度上掩盖了小直径无髓神经纤维的丢失。本研究在国际上首次把新的体视学方法和电子显微镜结合起来定量研究大鼠大脑白质无髓神经纤维的老年性改变。研究结果除进一步推动对老年大脑白质神经纤维改变的认识以外,还为在正常状态下大鼠白质无髓神经纤维长度和体积提供了基本数据,为以后应用这种动物模型作进一步的研究提供了参考资料。
Objective To describe how to apply new stereological methods to study the age-related changes of white matter myelinated nerve fibers in rats in order to find out the exact cause of the shortening of the total length of myelinated nerve fibers in aged white matter. Methods Ten Long-Ev-ans rats aged 6 to 8 months and 8 rats of the same age over 18 months were used in this study. The volume density and length density of unmyelinated nerve fibers in white matter and the total volume and total length of unmyelinated nerve fibers in white matter were calculated by electron microscopy and corresponding stereological methods. Results In this study, we found no significant shortening of the total length of white matter myelinated nerve fibers in male and female rats. In the white matter group, the total volume of unmyelinated nerve fibers in the female and general sex groups both had significant reduction in senility. Male The total volume of unmyelinated nerve fibers in rats, although not significant, decreased by up to 31%. Conclusions There is a significant loss of large diameter unmyelinated nerve fibers in the white matter of senile brain, meanwhile, the demyelination of myelinated nerve fibers with small diameter changes to a certain extent, which masks the loss of small diameter unmyelinated nerve fibers. This study for the first time in the world of new stereological methods and electron microscopy combined quantitative study of rat white matter unmyelinated nerve fibers of the elderly changes. In addition to further promoting the understanding of the changes of white matter nerve fibers in the aged brain, the results provide basic data for the length and volume of unmyelinated nerve fibers in white matter of rats under normal conditions, and provide a further study for further application of this animal model Reference material