Meek J, Nieuwenhuys R
Department of Anatomy and Embryology, University of Nijmegen, The Netherlands.
J Comp Neurol. 1991 Apr 1;306(1):156-92. doi: 10.1002/cne.903060111.
The present study is devoted to a detailed analysis of the structural and synaptic organization of mormyrid Purkinje cells in order to evaluate the possible functional significance of their dendritic palisade pattern. For this purpose, the properties of Golgi-impregnated as well as unimpregnated Purkinje cells in lobe C1 and C3 of the cerebellum of Gnathonemus petersii were light and electron microscopically analyzed, quantified, reconstructed, and mutually compared. Special attention was paid to the degree of regularity of their dendritic trees, their relations with Bergmann glia, and the distribution and numerical properties of their synaptic connections with parallel fibers, stellate cells, "climbing" fibers, and Purkinje axonal boutons. The highest degree of palisade specialization was encountered in lobe C1, where Purkinje cells have on average 50 palisade dendrites with a very regular distribution in a sagittal plane. Their spine density decreases from superficial to deep (from 14 to 6 per micron dendritic length), a gradient correlated with a decreasing parallel fiber density but an increasing parallel fiber diameter. Each Purkinje cell makes on average 75,000 synaptic contacts with parallel fibers, some of which are rather coarse (0.45 microns), and provided with numerous short collaterals. Climbing fibers do not climb, since their synaptic contacts are restricted to the ganglionic layer (i.e., the layer of Purkinje and eurydendroid projection cells), where they make about 130 synaptic contacts per cell with 2 or 3 clusters of thorns on the proximal dendrites. These clusters contain also a type of "shunting" elements that make desmosome-like junctions with both the climbing fiber boutons and the necks of the thorns. The axons of Purkinje cells in lobe C1 make small terminal arborizations, with about 20 boutons, that may be substantially (up to 500 microns) displaced rostrally or caudally with respect to the soma. Purkinje axonal boutons were observed to make synaptic contacts with eurydendroid projection cells and with the proximal dendritic and somatic receptive surface of Purkinje cells, where about 15 randomly distributed boutons per neuron occur. The organization of Purkinje cells in lobe C3 differs markedly from that in C1 and seems to be less regular and specialized, although the overall palisade pattern is even more regular than in lobe C1 because of the absence of large eurydendroid neurons. However, individual neurons have a less regular dendritic tree, there is no apical-basal gradient in spine density or parallel fiber density and diameter, and there are no "shunting" elements in the climbing fiber glomeruli.(ABSTRACT TRUNCATED AT 400 WORDS)
本研究致力于对 Mormyrid 浦肯野细胞的结构和突触组织进行详细分析，以评估其树突栅栏模式可能的功能意义。为此，对彼得氏裸臀鱼小脑 C1 和 C3 叶中经高尔基浸染以及未经浸染的浦肯野细胞的特性进行了光镜和电镜分析、量化、重建并相互比较。特别关注了它们树突树的规则程度、与伯格曼胶质细胞的关系，以及它们与平行纤维、星状细胞、“攀缘”纤维和浦肯野轴突终扣的突触连接的分布和数量特性。在 C1 叶中遇到了最高程度的栅栏特化，其中浦肯野细胞平均有 50 个栅栏状树突，在矢状面分布非常规则。它们的棘密度从浅到深逐渐降低（从每微米树突长度 14 个降至 6 个），这种梯度与平行纤维密度降低但平行纤维直径增加相关。每个浦肯野细胞平均与平行纤维形成 75,000 个突触接触，其中一些相当粗大（0.45 微米），并具有许多短侧支。攀缘纤维并不“攀爬”，因为它们的突触接触仅限于神经节层（即浦肯野和广树突投射细胞层），在该层中每个细胞与近端树突上的 2 或 3 簇棘形成约 130 个突触接触。这些簇中还包含一种“分流”元件，它们与攀缘纤维终扣和棘的颈部形成类似桥粒的连接。C1 叶中浦肯野细胞的轴突形成小的终末分支，约有 20 个终扣，相对于胞体，它们可能在头侧或尾侧有显著位移（可达 500 微米）。观察到浦肯野轴突终扣与广树突投射细胞以及浦肯野细胞的近端树突和胞体感受表面形成突触接触，每个神经元约有 15 个随机分布的终扣。C3 叶中浦肯野细胞的组织与 C1 叶明显不同，似乎不太规则和特化，尽管由于没有大型广树突神经元，整体栅栏模式比 C1 叶更规则。然而，单个神经元的树突树不太规则，在棘密度或平行纤维密度及直径方面没有顶 - 基梯度，并且在攀缘纤维小球中没有“分流”元件。（摘要截短至 400 字）
