AXOSPINOUS SYNAPSES WITH SEGMENTED POSTSYNAPTIC DENSITIES - A MORPHOLOGICALLY DISTINCT SYNAPTIC SUBTYPE CONTRIBUTING TO THE NUMBER OF PROFILES OF PERFORATED SYNAPSES VISUALIZED IN RANDOM SECTIONS
AXOSPINOUS SYNAPSES WITH SEGMENTED POSTSYNAPTIC DENSITIES - A MORPHOLOGICALLY DISTINCT SYNAPTIC SUBTYPE CONTRIBUTING TO THE NUMBER OF PROFILES OF PERFORATED SYNAPSES VISUALIZED IN RANDOM SECTIONS
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DOI：
10.1016/0006-8993(87)90838-9
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发表时间：
1987-10-13
期刊：
影响因子：
2.9
通讯作者：
DETOLEDOMORRELL, L
中科院分区：
文献类型：
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作者：
GEINISMAN, Y;MORRELL, F;DETOLEDOMORRELL, L
研究了大鼠齿状回分子层的轴突突触。连续切片分析的突触，表现出一个不连续性的突触后密度（PSD）在至少一个连续的切片，进行。在与序列剖面垂直的平面上重建每个不连续的PSD。所获得的结果证实了先前的观察结果，即在渗透材料的随机切片中可视化的“穿孔”突触的轮廓是通过对穿孔和马蹄形psd的突触切片产生的。此外，研究还发现，另外两种突触亚型，即具有缺口和分段PSD的突触，也导致了“穿孔”突触的数量。有缺口的PSD的突触接触的特点是在连续的PSD上有一个压痕，相对较小的尺寸和简单的形状。它们似乎与具有不连续PSD的突触类别无关。通过在突触前轴突末端和突触后树突棘之间的界面上存在2-5个离散的PSD片段来区分与分段PSD的突触接触。一些PSD段有1-3个孔，而另一些则呈马蹄形。我们推测，分节的PSD可能经过穿孔和马蹄形PSD的进化阶段，形成一个特殊的突触接触，具有异常高的效率。每一个PSD片段都是一个单独的突触复合体的组成部分，每一个都相当于一个小的、形状简单的突触。属于单个突触连接的几个突触复合物的协同激活可能为突触传递的放大提供了一种机制。
Axospinous synapses were examined in the molecular layer of the rat dentate gyrus. Serial section analysis of synapses, which exhibited a discontinuity of the postsynaptic density (PSD) in at least one consecutive section, was performed. Reconstruction of each discontinuous PSD was made in a plane perpendicular to that of serial sections. The results obtained confirm earlier observations that profiles of ''perforated'' synapses visualized in random sections of osmicated material are produced by sectioning of synapses with perforated and horseshoe-shaped PSDs. Additionally, it has been found that two other synaptic subtypes, namely synapses with notched and segmented PSD, contribute to the number of profiles of ''perforated'' synapses. Synaptic contacts with notched PSD are characterized by an indentation of an otherwise continuous PSD, relatively small dimensions and simple shape. They appear to be unrelated to the category of synapses with discontinuous PSD. Synaptic contacts with segmented PSD are distinguished by the presence of 2-5 discrete PSD segments at the interface between a presynaptic axon terminal and a postsynaptic dendritic spine. Some PSD segments exhibit 1-3 perforations, while others are horseshoe-shaped. It is postulated that the segmented PSD may evolve through the stages of perforated and horseshoe-shaped PSD to form a specialized synaptic contact of an unusually high efficacy. Every PSD segment is a component of a separate synaptic complex, each one comparable to that of a small, simple-shaped synapse. A concerted activation of several synaptic complexes belonging to a single synaptic junction may provide a mechanism for an amplification of synaptic transmission.