Ultrastructure and quantification of synapses in the insect nervous system
Ultrastructure and quantification of synapses in the insect nervous system
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DOI：
10.1016/s0165-0270(96)00021-0
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发表时间：
1996-10-21
影响因子：
3
通讯作者：
Meinertzhagen, IA
中科院分区：
文献类型：
--
作者：
Meinertzhagen, IA
标准电镜方法可以成功地用于揭示不同昆虫物种突触连接的各种细胞器。突触类的各个接头表现出高度的形态刻板性，但通常需要研究连续切片才能了解接头轮廓在不同平面上切割时的不同外观。在单个切片中看到的大多数突触轮廓可以归因于一个或几个形态学类别，而不是许多。可能大多数中枢突触都是多接触型的，包含许多突触后成分，这些成分组合的多样性提供了特定突触连接之间的主要差异。当在倾斜的、非典型的截面上连续切割时，突触的不同轮廓为研究者提供了搜索图像，这是在单个截面中全面识别突触位点所需要的先验知识。后者可以用来描述一个未知的神经堆的突触组织，从不同神经元之间形成的各种突触接触。这就要求在突触后树突和它的母轴突之间建立连续性，然后轴突的位置可以用来识别起源的神经元。树突和轴突之间的追踪可以在有限区域的连续切片中系统地进行，也可以通过对单个切片的长期搜索来进行。单个部分中的突触轮廓的数量可以用于估计突触接触的数量，或者以相对的方式，作为不同细胞中每个部分的轮廓的数量，或者作为每个细胞的突触的绝对数量。后者需要使用的校正公式，考虑到节的厚度和突触连接的平均大小的影响，在一个特定的部分记录的突触配置文件的数量。
Standard EM methods can be successfully used to reveal the various organelles of synaptic junctions in different insect species. The individual junctions of a synaptic class exhibit a high level of morphological stereotypy, but the study of serial sections is generally necessary to understand the different appearances of a junction's profiles when it is cut in different planes. Most synaptic profiles seen in single sections may then be attributed to one or a few morphological classes, not to many. Probably most central synapses are of the multiple-contact type, containing a number of postsynaptic elements, with the diversity of the combinations of these providing the major difference between particular synaptic junctions. The different profiles of a synapse when cut serially in oblique, non-canonical section planes provide the investigator with search images, prior knowledge of which is needed for a comprehensive identification of synaptic sites in single sections. The latter can be used to describe the synaptic organization of an unknown neuropile from the variety of synaptic contacts that form between different neurons. This requires that continuity be established between a postsynaptic dendrite and its parent axon, and that the position of the axon can then be used to identify the neuron of origin. Tracing between dendrite and axon can be undertaken either systematically in serial sections of a restricted region or by protracted searches of single sections. The number of synaptic profiles in a single section can be used to estimate the number of synaptic contacts, either in relative terms, as the number of profiles per section in different cells, or as the absolute number of synapses per cell. The latter requires use of correction formulae, taking into account the influence of section thickness and of the mean size of the synaptic junction on the number of synaptic profiles recorded in a particular section.