AN EM ANALYSIS OF THE SYNAPTIC CONNECTIONS OF HORSERADISH PEROXIDASE-FILLED STALKED CELLS AND ISLET CELLS IN THE SUBSTANTIA GELATINOSA OF ADULT CAT SPINAL-CORD
AN EM ANALYSIS OF THE SYNAPTIC CONNECTIONS OF HORSERADISH PEROXIDASE-FILLED STALKED CELLS AND ISLET CELLS IN THE SUBSTANTIA GELATINOSA OF ADULT CAT SPINAL-CORD
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DOI：
10.1002/cne.901940406
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发表时间：
1980-01-01
影响因子：
2.5
通讯作者：
HUMPHREY, E
中科院分区：
文献类型：
--
作者：
GOBEL, S;FALLS, WM;HUMPHREY, E
用微电极刺穿Rexed层II（IIa）外部的两个主要中间神经元，表征其主要输入，随后用辣根过氧化物酶填充。电镜观察其精细结构特征和突触联系。两个胰岛细胞，其rostrocaudally定向树突主要局限于IIa层内，收到小的有髓轴突的主要输入。有柄细胞胞体位于I/II界，其树突状结构呈锥形，横贯IIa层和Rexed's层II（IIb）的内部，吻尾侧树突状分支沿着I/IIa界走行。它接受来自小的有髓和无髓轴突的初级输入。这两种细胞类型收到不对称的轴树突触的初级末梢在IIa和IIb层肾小球和广泛分离的对称轴树突触的小非初级末梢以外的肾小球。在IIa层胰岛细胞的树突中突触囊泡的聚集体的存在下，但不是在柄细胞树突中，构成了这些中间神经元之间的主要精细结构差异。胰岛细胞树突在几种不同的神经突起上形成对称的突触。它们通常将单个2型棘（含有突触囊泡的棘）或树突轴送入IIa和IIb层肾小球，在那里它们在相邻的1型棘（没有突触囊泡的棘）和其他小树突轴上形成树突树突突触。一些胰岛细胞2型棘也在初级末梢上形成树突轴突突触。在肾小球外，胰岛细胞树突也在1型棘和不同大小的树突轴上形成树-树突触。它们经常接近其他树突轴，形成小束树突，其中它们通过树-树突触与其他含有突触囊泡的树突连接。胰岛细胞在其树突轴的珠状扩大处和沿着一些细径树突轴，在无髓鞘轴突的轴上形成树突轴突突触。胰岛细胞的无髓轴突在肾小球外的第二层树突轴和棘上形成对称的突触。IIa层胰岛细胞作为抑制性中间神经元的作用进行了讨论。有柄细胞也在肾小球IIa和IIb层接受其主要输入。与胰岛细胞不同，它通常将几个棘头（1型）送入单个肾小球。由于树突中缺乏突触小泡，有柄细胞的整个突触输出是通过在第I层中发现的无髓鞘轴突的末梢。有柄细胞可能作为兴奋性中间神经元，将来自IIa和IIb层中的初级轴突末梢的输入传递到I层投射神经元的树突和其树突在I层中分支的其他背角神经元。它可能是Ⅱ a层胰岛细胞重要的突触靶点。
Two major interneurons of the outer part of Rexed''s layer II (IIa) were impaled with microelectrodes, had their primary inputs characterized and were subsequently filled with horseradish peroxidase. Their fine structural characteristics and synaptic connections were then analyzed by EM. Two islet cells, whose rostrocaudally oriented dendrites were largely confined within layer IIa, received primary input from small myelinated axons. A stalked cell, whose cell body was situated on I/II border had a cone-shaped dendritic arbor which traversed layer IIa as well as the inner part of Rexed''s layer II (IIb) and rostrocaudal dendritic branches which ran for part of their course along the I/IIa border. It received primary input from small myelinated as well as from unmyelinated axons. Both cell types received asymmetrical axodendritic synapses from primary endings in layer IIa and IIb glomeruli and widely separated symmetrical axodendritic synapses from small nonprimary endings outside of glomerli. The presence of aggregates of synaptic vesicles in the dendrites of the layer IIa islet cells but not in the stalked cell dendrites constitutes the major fine structural difference between these interneurons. Islet cell dendrites form symmetrical synapses on several different kinds of neural processes. They usually send either a single type 2 spine (spines which contain synaptic vesicles) or dendritic shaft into layer IIa and IIb glomeruli, where they form dendrodendritic synapses on adjacent type 1 spines (spines without synaptic vesicles) and on other small dendritic shafts. Some islet cell type 2 spines also form dendroaxonic synapses on the primary endings. Outside of the glomeruli, islet cell dendrites also form dendrodendritic synapses on type 1 spines and different sized dendritic shafts. They often approach other dendritic shafts forming small bundles of dendrites in which they are reciprocally linked by dendrodendritic synapses to other synaptic vesicle-containing dendrites. At bead-like enlargements of their dendritic shafts and along some of their fine caliber dendritic shafts, the islet cells form dendroaxonic synapses on the shafts of unmyelinated axons. The unmyelinated axon of the islet cell forms symmetrical synapses on layer II dendritic shafts and spines outside of glomeruli. The role of the layer IIa islet cell as an inhibitory interneuron is discussed. The stalked cell also receives its primary input in the layer IIa and IIb glomeruli. Unlike the islet cell, it usually sends several spine heads (type 1) into a single glomerulus. Lacking synaptic vesicles in its dendrites, the entire synaptic output of the stalked cell is through the endings of its unmyelinated axon which are found in layer I. The stalked cell may function as an excitatory interneuron conveying inputs from primary axonal endings in layers IIa and IIb to the dendrites of the layer I projection neurons and to other dorsal horn neurons whose dendrites arborize in layer I. It may be an important synaptic target of the layer IIa islet cell.