牦牛海马结构形态特征和成体神经发生的研究 |
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牦牛海马结构形态特征和成体神经发生的研究 Study on Morphology and Adult Neurogenesis of hippocampus in Yak 发布时间：2011-07-20 浏览量：167 收藏数：0 评论数：0 总览 评价 许文强1， 徐鑫佳1， 范力1， 邵虹1， 刘兵峰1， 邵宝平1， 王建林1， 赵善廷2* （ 1、兰州大学生命科学学院； 2、兰州大学生命科学学院，兰州 730000；西北农林科技大学动物医学学院，杨凌 712100； ）
摘要： 目的 对成年牦牛海马的形态结构、细胞构筑、齿状回内的神经干细胞和新生神经元进行组织学与免疫组织化学观察，为高原动物海马结构的形态学研究，以及齿状回中成体神经发生的研究提供形态学方面的理论依据。方法 4% PFA溶液和Golgi液分别固定新鲜海马组织，进行传统H-E染色、Golgi-Cox染色、以及针对新生神经元、成熟神经元和胶质细胞等各自的标记物的免疫组化染色和荧光标记，体视显微镜、普通内置数码光镜和激光共聚焦显微镜观察并摄影。结果 牦牛海马结构主要包括齿状回和海马本部，二者分层清晰。海马的主要细胞为颗粒细胞、苔藓细胞和锥体细胞。CA3区的锥体细胞比CA1区的大，但后者顶树突的平均长度较长。CA1区的锥体细胞明显地分为两层，而不像CA3区那样呈密集的一层。内层锥体细胞靠近海马分子层，排列较紧密，外层的锥体细胞排列较松散。DCX免疫组化染色表明在牦牛海马中存在着成体神经发生。DCX阳性细胞的胞体主要集中在齿状回颗粒下层靠近门区处，沿颗粒层内侧单个或少数聚集分布，同时，门区和颗粒层中只有少数分布。GFAP免疫荧光标记表明在整个海马结构中都有大量星形GFAP阳性细胞散在分布，特别的是海马分子层和门区内靠近颗粒层部分的密度较其它部位大。沿齿状回颗粒下层分布着一层放射状胶质细胞，其胞核呈GFAP阴性，而胞质为GFAP阳性，胞体朝向分子层单极性发出1-2个细长的GFAP阳性突起，突起末端终止于颗粒层或分子层中。结论 牦牛海马的形态结构与绵羊的相似，而与大鼠、小鼠、家猫、兔子等小型哺乳动物有一定差别，这可能是牦牛和绵羊同属哺乳纲偶题目牛科动物，在遗传进化过程中形成的结果。此外，成年牦牛齿状回中有新的神经元产生且比较多，可能是由于其特殊的生存环境和残酷的自然选择所致。
关键词： 牦牛；齿状回；双皮质素；成体神经发生 XU Wenqiang1， XU Xinjia1， FAN Li1， SHAO Hong1， LIU Bingfeng1， SHAO Baoping1， WANG Jianlin1， ZHAO Shanting2* （ 1、School of Life Science, Lanzhou University； 2、School of Life Science, Lanzhou University; College of Veterinary Medicine, Northwest A &F University； ）
Abstract： Objective The present study explored the morphology and cell types of yak hippocampus, as well as the neural stem cells and newborn neurons located in SGZ of dentate gyrus using histology and immunohistochemistry, providing theoretical basis for both the morphological research of hippocampal formation and adult neurogenesis in dentate gyrus of plateau animals. Methods Fresh yak hippocampal formations were fixed in 4% Paraformaldehyde and Golgi solution, then the traditional H-E staining, Golgi-Cox staining, immunohistochemistry and immunofluorescence labeling against markers for newborn neurons, mature neurons and glias were carried out. The stained sections were observed and photographed using stereoscope, conventional microscope and laser scanning confocal microscope. Results The yak hippcampus mainly consists of dentate gyrus and hippocampus proper, both of them stratify clearly. The granule cells, mossy cells and pyramidal cells are the three major cell types in hippocampus formation. The pyramidal cells in CA3 region are bigger than those in CA1 region, but the average length of apical dendrites of latter are longer. The pyramidal cells in CA1 region are obviously divided into two sublayers rather than form a dense uniform layer like in CA3 region. The pyramidal cells in the inner zone next to hippocampal molecular layer are arranged in cluster, instead, those in the outer zone are distributed loosely. Immunostaining for DCX indicated that adult neurogenesis occurs in yak hippocampus. The somas of most DCX-positive cells are distributed individually or in group in the deepest part of the granular layer close to hilus. Meanwhile, some positive cells are located in hilus or granular layer. The immunofluorescence labeling for GFAP showed that huge number of star GFAP-positive cells scattered in the whole hippocampal formation. Furthermore, the density of GFAP-positive cells in molecular layer, the boundary zone between hilus and granular layer are higher than other layers. Along the subgranular zone of the dentate gyrus, a layer of GFAP-expressing radial glia-like cells located. Their cytoplasms are GFAP-positive while the nuclei are negative, and each soma sent 1or 2 processes to the molecular layer, which are also positive. The terminals of these processes terminated in the granular layer or molecular layer. Conclusion The hippocampal formation of yak has its characters compared with small mammals, such as rat, mouse, cat, rabbit, but is similar to that of sheep. It might be the result of evolution. In addition, the adult neurogenesis existing in yak dentate gyrus seems more powerful because of its unique environment and rigid natural selection.
Keywords： Yak;dentate gyrus;doublecortin;adult neurogenesis
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