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目的:建立定量研究海马结构及其内有髓神经纤维的无偏体视学方法.方法:选择6 mo龄正常雌性Long-Ev-ans大鼠5只,运用卡瓦列里原理计算海马结构的总体积.根据随机抽样原则在海马结构内切取5～6个组织块,用“球切法”保证满足三维空间内各向同性抽样原则后,切取60 nm厚的超薄切片,在透射电子显微镜下从每张切片随机拍摄15个视野.使用无偏计数框计算海马结构内有髓神经纤维的长度密度;使用等距测点框计算海马结构内有髓神经纤维的体积密度.用长度密度,体积密度分别乘以海马结构的体积,获得海马结构内有髓神经纤维的总长度和总体积.测量与纤维断面的最长轴相垂直的所有横轴中最长的一条横径为其直径.结果:得到大鼠海马结构的平均体积为(85.9±14.0)mm3;海马结构内有髓神经纤维的总长度为(9.1±3.8)km;总体积为(4.3±1.2)mm3;平均直径为(0.7±0.1)μm.结论:本研究建立的体视学方法可为定量研究正常老年及各种神经系统退行性疾病状态下海马结构内有髓神经纤维的改变提供依据.
Objective: To establish an unbiased visual method to quantitatively study the structure of the hippocampus and its myelinated nerve fibers.Methods: Five normal female Long-Ev-ans rats aged 6 months were selected to calculate the hippocampal formation by using the Cavalry principle Total volume.According to the principle of random sampling in the hippocampal structure cut 5 to 6 tissue blocks, with “ball cut method” to ensure that three-dimensional space to meet the principle of isotropic sampling, the cut 60 nm thick slices, in the transmission Fifteen fields were randomly selected from each section under an electron microscope, and the length density of myelinated nerve fibers in the hippocampal formation was calculated using an unbiased counting box. The bulk density of myelinated nerve fibers in the hippocampal formation was calculated using an equidistant point frame. Density and bulk density multiplied by the volume of the hippocampal structure respectively to obtain the total length and the total volume of the myelinated nerve fibers in the hippocampal formation.The longest of all the transverse axes perpendicular to the longest axis of the fiber cross section is measured as Diameter of rat hippocampus was (85.9 ± 14.0) mm3, the total length of myelinated nerve fibers in hippocampus was (9.1 ± 3.8) km, the total volume was (4.3 ± 1.2) mm3, the average diameter (0.7 ± 0.1) μm. Conclusion: This study The established method of stereology can provide a basis for quantitative study of the changes of myelinated nerve fibers in the hippocampal formation under the condition of normal aging and various degenerative diseases of the nervous system.