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本研究用 HE染色和超薄切片技术 ,对 4～ 8月胎儿小脑皮质神经细胞的发育和细胞构筑进行了观察。结果发现从胚胎 4月开始 ,小脑已由两侧的小脑半球和蚓部组成 ,可见皮质和髓质。皮质分为外颗粒层、分子层、中间层、内颗粒层四层。随月龄增加 ,外颗粒层的相对厚度下降 ,绝对厚度增加。8月时 ,皮质可分为外颗粒层 ,分子层 ,蒲肯野细胞层和内颗粒层。电镜观察发现 4月胎儿小脑皮质的神经细胞排列紧密 ,细胞核大而圆 ,突起少 ,此时突触处于形成期 ,突触前膜、突触后膜和突触间隙已清晰可辨 ,但突触小泡很少。6月时 ,神经细胞增大 ,胞质中细胞器的种类和数目较 4月时有明显的增多。绝大多数突触依然是突触样连结 ,特点是两膜呈对称性增厚 ,突触间隙清晰可见 ,突触前终末内线粒体结构较幼稚 ,突触小泡数目较少。8月时的神经元发育基本成熟 ,细胞突起的数目增多且较长。突触结构趋于成熟 ,突触前后膜增厚 ,突触前终末内的小泡增多 ,且向前膜聚集 ,突触样连结数目减少 ,典型突触增多。以上这些结果表明 ,小脑皮质的神经细胞随胎龄增加 ,其结构和功能逐步完善 ,7～ 8月间是发育的重要时期
In this study, HE staining and ultrathin section technique were used to observe the development and cell construction of fetal cerebellar cortical neurons from April to August. The results showed that from the beginning of the embryo in April, the cerebellum has by both sides of the cerebellar hemispheres and vermis, visible cortex and medulla. Cortex is divided into outer particle layer, molecular layer, the middle layer, the inner layer of particles four. With the increase of age, the relative thickness of the outer particle layer decreased, the absolute thickness increased. August, the cortex can be divided into outer particle layer, molecular layer, Purkinje cell layer and the inner particle layer. Electron microscopy showed that the neurons in the fetal cerebellar cortex arranged closely in April, with large and round nuclei and few protrusions. At this time, the synapses were in the formation phase, and the presynaptic and postsynaptic membranes and synaptic clefts were clearly discernible. However, Tentative vesicles rarely. In June, nerve cells increased, and the number and types of organelles in the cytoplasm increased significantly compared with those in April. The vast majority of synapses are still synaptic-like, characterized by thickening of the symmetry of the two membranes, the synaptic cleft is clearly visible, pre-synaptic mitochondrial structure more naive, fewer synaptic vesicles. Neurons in August developed basically mature, the number of cell protrusions increased and longer. Synaptic structure tends to mature, thickening of the anterior and posterior synapses, vesicles within the presynaptic terminals increased, and forward membrane aggregation, the number of synaptic connections decreased, the typical increase in synapses. These results show that the cerebellar cortex neurons with increased gestational age, its structure and function gradually improved, from July to August is an important period of development