Sotelo C
Brain Res. 1975 Aug 22;94(1):19-44. doi: 10.1016/0006-8993(75)90874-4.
The vermis of the homozygous weaver mice has been examined with Golgi and electron microscopic techniques. In addition to the findings already reported by previous authors 12, 29, new cytological features concerning all the cerebellar neuronal types and the synaptic reorganization of the cerebellar circuitry are described. As in other agranular cerebella, Purkinje cells do not develop spiny branchlets and have a randomly oriented dendritic tree. By contrast, their thick dendrites are studded with spines; according to their size and shape these were classified into: (a) small stubby spines which are the normal postsynaptic targets for climbing fibers; (b) tertiary-like spines, most of which are free of axonal contacts; (c) dolichoderus spines; (d) branching spines; and (e) hypertrophic spines. The last 3 types do not exist in normal cerebellum. Postsynaptic-like differentiations are frequently undercoating the smooth surface of the Purkinje dendrites. As it happens in the case of the free spines, free postsynaptic sites in the shafts of the dendrites develop an extracellular material similar to the material present in synaptic clefts. Basket and stellate cells also develop postsynaptic-like differentiations undercoating the somatic and dendritic plasma membranes. These free postsynaptic sites can reach a gigantic size, being longer than 3 mum in length. The rare postmigrative granule cells which persist in wv exhibit claw-endings not only at the dendritc terminal segments, but at the proximal dendritic stems as well. Some of these granule cells, besides having fully achieved migration, undergo a degenerative process indicating that they are probably directly affected by the mutation. Concerning the cerebellar circuitry, and despite the great number of free postsynaptic sites, the large majority of the synaptic contacts keep their specificity. However, some quantitative variations have been disclosed. The surface density of climbing varicosities is increased, whereas that of mossy rosettes is decreased. Stellate and basket fibers are present and their density also decreased. Furthermore, the pinceau formation around the initial segment of the Purkinje cell axon is missing. In addition to all normal synapt iccontacts (with the exception of the'parallel fiber-omnicellularsystem') present in weaver, heterologous synapses have also been encountered, mainly concerning the Purkinje dendritic spines, which can be contacted by mossy rosettes, granule cell bodies and/or dendrites. Morphological signs of partial innervation of the free postsynaptic sites on the smooth surface of Purknje dendrites and the perikarya and dendrites of interneurons have also been observed. These results confirm the existence of synaptic remodeling in wv cerebellum
采用高尔基染色法和电子显微镜技术对纯合子韦弗小鼠的蚓部进行了研究。除了先前作者已报道的研究结果外，还描述了有关所有小脑神经元类型的新细胞学特征以及小脑神经回路的突触重组。与其他无颗粒小脑一样，浦肯野细胞没有发育出棘状小分支，并且具有随机取向的树突。相比之下，它们的粗大树突上布满了棘；根据其大小和形状，这些棘可分为：（a）小而粗短的棘，它们是攀缘纤维的正常突触后靶点；（b）三级样棘，其中大多数没有轴突接触；（c）细长棘；（d）分支棘；（e）肥大棘。后三种类型在正常小脑中不存在。突触后样分化经常位于浦肯野树突的光滑表面下方。就游离棘的情况而言，树突轴中的游离突触后位点会形成一种类似于突触间隙中存在的细胞外物质。篮状细胞和星状细胞在其胞体和树突质膜下方也会形成突触后样分化。这些游离突触后位点的长度可以达到巨大尺寸，超过3微米。在wv小鼠中持续存在的罕见的迁移后颗粒细胞不仅在树突末端节段，而且在近端树突干上都表现出爪状末梢。其中一些颗粒细胞除了已经完全完成迁移外，还经历了退化过程，这表明它们可能直接受到突变的影响。关于小脑神经回路，尽管存在大量游离突触后位点，但绝大多数突触接触仍保持其特异性。然而，已经发现了一些数量上的变化。攀缘膨大的表面密度增加，而苔藓状玫瑰花结的表面密度降低。星状纤维和篮状纤维存在，但其密度也降低。此外，浦肯野细胞轴突起始段周围的刷状缘结构缺失。除了wv小鼠中存在的所有正常突触接触（平行纤维-全细胞系统除外）外，还遇到了异源突触，主要涉及浦肯野树突棘，它们可以被苔藓状玫瑰花结、颗粒细胞体和/或树突接触。还观察到浦肯野树突光滑表面以及中间神经元的胞体和树突上的游离突触后位点部分神经支配的形态学迹象。这些结果证实了wv小鼠小脑中存在突触重塑。
