SYNAPTIC ARCHITECTURE OF GLOMERULI IN SUPERFICIAL DORSAL HORN OF RAT SPINAL-CORD, AS SHOWN IN SERIAL RECONSTRUCTIONS
SYNAPTIC ARCHITECTURE OF GLOMERULI IN SUPERFICIAL DORSAL HORN OF RAT SPINAL-CORD, AS SHOWN IN SERIAL RECONSTRUCTIONS
复制标题
DOI：
10.1007/bf01258448
复制
发表时间：
1985-01-01
期刊：
影响因子：
--
通讯作者：
COIMBRA, A
中科院分区：
文献类型：
--
作者：
RIBEIRODASILVA, A;PIGNATELLI, D;COIMBRA, A
用连续切片电镜观察了大鼠背角Ⅱ板层内肾小球的突触结构。4个C1-终末（小，暗，弯曲），4个CIIa（大，轻，规则，无神经丝）和4个CIIb（有神经丝）在I，IIa和IIb型突触肾小球的中心，分别连续切片和重建。在所有类型的肾小球中，中央终末（C）和没有突触小泡的树突轮廓（D）之间的不对称突触普遍存在。与突触前树突的对称的树突轴突接触（V1 → V2）。C）实际上仅发生在1型肾小球中，其中也存在更多的不对称C →。V1接触比II型肾小球。对称轴轴突触V2 →C在Ⅱ a和Ⅱ b型肾小球中含量较高。Ⅱ a型肾小球有明显较多的C →。D型突触和所有突触每单位面积的C表面，比IIb型肾小球。三叉神经系统与C和D突触后V2几乎一样多，涉及V1在I型肾小球。V2三联征在IIa型中占很大比例，在IIb型中几乎不存在。这三种类型的肾小球都有自己的突触相互作用模式，可能反映了前馈和反馈机制的特定复合体。在I型肾小球中，伤害性C1终末对二级神经元的兴奋可能以类似的比例受到C终末本身在没有肾小球的情况下兴奋的突触前树突或肾小球外兴奋的外周轴突的控制。这种控制可能在IIa型肾小球中占主导地位，并且是IIb型肾小球中唯一有效的调节机制。
Using serial section EM analysis, synaptic organization of glomeruli in lamina II of the dorsal horn of the rat was examined. Four C1-terminals (small, dark and sinuous), 4 CIIa (large, light and regular, without neurofilaments) and 4 CIIb (with neurofilaments) at the centers of synaptic glomeruli of types I, IIa and IIb, respectively, were serially sectioned and reconstructed. Asymmetrical synapses between the central terminal (C) and dendritic profiles without synaptic vesicles (D) prevailed in all types of glomeruli. Symmetrical dendroaxonic contacts with presynaptic dendrites (V1 .fwdarw. C) occurred practically only in type 1 glomeruli in which there were also more asymmetrical C .fwdarw. V1 contacts than in type II glomeruli. Symmetrical axoaxonic synapses V2 .fwdarw. C were more abundant in type IIa and IIb glomeruli. Type IIa glomeruli had a significantly larger number of C .fwdarw. D synapses and of all synapses per unit area of C surface, than type IIb glomeruli. Triadic systems with C and D postsynaptic to V2 were nearly as numerous as those involving V1 in type I glomeruli. Triads with V2 were largely preponderant in type IIa and virtually exclusive in type IIb. Each of the 3 types of glomerulus has its own pattern of synaptic interactions which might reflect specific complexes of feed-forward and feedback mechanisms. In type I glomeruli, excitation of 2nd-order neurons by nociceptive C1 terminals may be controlled in similar proportions by presynaptic dendrites excited without the glomerulus by the C terminal itself, or by peripheral axons excited from outside th8e glomerulus. This kind of control is likely to prevail in type IIa glomeruli and to be the only efficient modulatory mechanism in type IIb glomeruli.