大鼠三叉神经脊束核Ⅱ尾侧亚核层内CB样、PV样阳性结构的分布及其突触联系

本研究用免疫组织化学方法观察了 Calbindin D-2 8k( CB)样和 Parvalbumin ( PV)样胞体、纤维和终末在三叉神经脊束核尾侧亚核 ( Vc) 层内的分布及它们的突触联系。在光镜下观察到 CB样和 PV样阳性胞体、纤维和终末在 II层内侧带 ( IIi)最为密集 ,PV样阳性神经元的胞体稍大 ,但数量少于 CB样阳性神经元。在电镜下观察到 CB样或 PV样阳性结构主要形成下列 4种突触联系 :( 1)阳性轴突终末与阳性或阴性轴突终末形成对称性轴 -轴突触和少量非对称性轴 -轴突触 ;( 2 )阳性轴突终末与阳性树突形成非对称性和对称性轴 -树突触 ;( 3 ) CB样阳性轴突终末与阴性树突主要形成非对称性轴 -树突触 ,PV样阳性轴突终末与阴性树突主要形成对称性轴 -树突触 ;( 4 )阴性轴突终末与阳性树突形成非对称性和对称性轴 -树突触。另外还可见到 CB样或PV样阳性或阴性树突、轴突及终末与 CB样、PV样阳性或阴性的初级传入纤维终末形成 型和 II型突触小球。 型突触小球数量较多 ,有典型的扇贝样初级传入纤维终末和不均一的小泡 ,线粒体少 ;II型突触小球的初级传入纤维终末粗大而清亮 ,外观不规则 ,有均匀一致的小泡和丰富的线粒体。根据上述结果可以推知在面口部伤害性信息的传递和调控过程中 ,Vc II层神经元发挥着重要的作用

DISTRIBUTION OF CB -LIKE AND PV-LIKE POSITIVE STRUCTURES AND THEIR SYNAPTICAL RELATIONS IN LAMINA II OF TRIGEMINAL SUBNUCLEUS CAUDALIS IN THE RAT

Both calbindin D 28k like immunoreactive(CB LI) and parvalbumin like(PV LI) neurons are generally accepted as the markers of lamina II neurons. To investigate the morphological features and synaptic connections of lamina II neurons in the Vc, we used immunohistochemical staining and electron microscopy technique to examine the distributions of CB LI and PV LI structures and their synaptic connections in lamina II. We were particularly interested in their synaptic connections in lamina II of the Vc. CB LI neuronal cell bodies, fibers and terminals were distributed in laminae Ⅰ～Ⅲ, but were more often encounted in the inner part of lamina II(IIi). Most of the CB LI neuronal cell bodies were small(10～20 μm) and elliptical and round in shape. PV LI neuronal cell bodies, fibers and terminals were mainly located in lamina II, especially abundant in IIi, generally having larger somata (20～35 μm) than CB LI ones. They were triangular, multipolar or long elliptical in shape. In lamina Ⅰ and outer part of lamina II(IIo) and lamina III, CB LI and PV LI structures were only sparsely found. Under electron microscope, several kinds of synaptic connections were observed: (1) positive axon profiles made symmetrical axo axonal synapses and a few asymmetrical axo axonal synapses with positive/negative axon terminals; (2) positive axon terminals made asymmetrical axo dendritic synapses and symmetrical axo dendritic synapses with positive dendrites; (3) positive axon terminals made symmetrical and asymmetrical axo dendritic synapses with negative dendrites; (4) negative axon terminals made asymmetrical and symmetrical axo dendritic synapses with positive dendrites. Primary afferent terminals also formed two kinds of glomeruli (type Ⅰ, II) with CB LI or PV LI and negative terminals/dendrites. Glomeruli Ⅰ were more abundant and of high electronic density, with typical scalloped contours and closely packed spherical vesicles of variable diameter and a few mitochondria. Among the peripheral terminals, there were dendritic spines and a few presynaptic dendritic spines (V1) and axon endings rich in discoid vesicles (V2). CB LI structures were mainly involved in constituting glomeruli Ⅰ. Glomeruli II were electron lucent. Large central terminals of irregular contour, with synaptic vesicles of more uniform diameter and more mitochondria, were surrounded by dendrites, axon terminals and dendritic spines. According to these results it was deduced that during the transmission and modulation of oral facial stimulated information, neurons of lamina II were considered as playing important roles between primary afferent terminals and projecting neurons. (Figures 1,2 on plate 10,11)