Ultrastructure of commissural neurons of the hilar region in the hippocampal dentate gyrus
Ultrastructure of commissural neurons of the hilar region in the hippocampal dentate gyrus
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海马齿状回门区连合神经元的超微结构
DOI：
10.1016/0014-4886(83)90083-3
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发表时间：
1983
影响因子：
5.3
通讯作者：
C. Ribak
中科院分区：
文献类型：
--
作者：
K. Seroogy;L. Seress;C. Ribak
以前的研究已经在光镜水平上描述了齿状回门部的多态神经元，并表明其中许多神经元是同侧向齿状回的联合和连合投射的起源细胞。由于以前的研究没有描述肺门神经元的超微结构特征，所以我们确定了肺门连合神经元的这些特征。采用辣根过氧化物酶(HRP)逆行运输的方法，用银染技术进行HRP的增强。在对侧门的电子显微镜切片中观察到两类标记的连合神经元。一种类型是由具有体细胞的细胞组成，核呈圆形或椭圆形，无核内包涵体，形成对称性轴体突触。这些神经元的主要树突粗大，呈锥形。相反，另一种类型的标记神经元胞体具有内含核内杆状或片状的核，显示对称性和非对称性轴体突触，树突不那么粗大，通常呈树突状。在相同的准备中，标记的连合轴突终末与门部和分子层中的树突和树突形成突触，并与颗粒细胞层中的胞体形成突触。从本研究的结果可以看出，肺门连合神经元有两种不同的类型：一种类似于刺状CA3锥体神经元的形态，是一种兴奋性投射细胞；另一种类似于齿状回篮细胞，是一种与GABA能抑制相关的局部回路神经元。后一种细胞类型进一步支持了一些连合神经元具有抑制性的观点。
Previous studies have described the polymorph neurons in the hilus of the dentate gyrus at the light microscopic level and have indicated that many of those neurons are the cells of origin for both ipsilateral associational and commissural projections to the dentate gyrus. Because previous studies have not described the ultrastructural characteristics of the hilar neurons, we identified these features of the commissural neurons in the hilus. The method of retrograde transport of horseradish peroxidase (HRP) was utilized with a silver staining technique for HRP intensification. Two populations of labeled commissural neurons were observed in electron microscopic preparations of the contralateral hilus. One type consisted of cells with somata that exhibited round or oval nuclei with no intranuclear inclusions and formed symmetric axosomatic synapses. The main dendrites of those neurons were thick and tapering. In contrast, the other type of labeled neuronal soma had infolded nuclei containing intranuclear rods or sheets, displayed both symmetric and asymmetric axosomatic synapses, and had dendrites that were less thick and generally aspinous. In those same preparations, labeled commissural axon terminals formed synapses with dendrites and dendritic spines in the hilus and molecular layer and iwth somata in the granule cell layer. From the results of this study it appears that there are two distinct populations of commissural hilar neurons: one type resembles the morphology of the spiny CA3 pyramidal neuron, a type of excitatory projection cell, and the other type is similar to the dentate gyrus basket cell, a local circuit neuron associated with GABAergic inhibition. This latter cell type provides further support for the notion that some commissural neurons are inhibitory.