大鼠三叉神经初级纤维传入终末的溃变类型和突触联系

TYPES AND SYNAPTIC CONNECTIONS OF DEGENERATING PRIMARY TRIGEMINAL AFFERENT TERMINALS IN RATS

损毁大鼠三叉神经根,观察其纤维终末在中枢内的溃变。结果发现:存活第1天,溃变终末内线粒体肿胀,嵴断裂紊乱,透明小泡聚集;第2天溃变终末电子密度增加,出现典型的神经微丝增生型溃变;第3天溃变的细小轴突终末密度显著增高;第4天细小的溃变轴突终末皱缩并被胶质细胞包绕,有的终末突触小泡融合成大小不等的空泡。另外,较大的扇贝型溃变终末常与多个树突形成轴一树突触,其中有的进一步形成轴—树—树连续性突触,轴—轴突触偶见,表明三叉神经初级传入纤维与中枢内其它神经元联系密切而广泛,与其复杂的痛觉调控机制相一致。

The trigerninal nerves of rats were dilapidated by means of injecting absolute alcohol into the nervous root and the types of degenerating afferent terminals and their synaptic connections were investigated with electron microscope. The results showed that the mitochondria swelled, mitochondri(?)l cristae disordered or even broke down and the clear vesicles gathered together closely on the 2nd day after the dilapidation; their electronic density in degenerating terminals increased obviously and typical neurofilamentous degenerating terminals appeared at the same time on the 3rd day; some degenerating small axonal terminals emerged in large quantities on the 4th day;this small terminals shrank and were wrapped up in glial cells,and all of the synaptic vesicles in the terminals fused into large or small empty ones on the 5th day. We also found that the large neurofilamentous degenerating terminals can form more than five site of contact with dendrites and axons,such as axo-dendritic, axo-dendrio-dendritic and axo-axonal synapses. The studies indicate that the primary trigeminal afferent terminals have extensive and close connections with other neurons situated in central areas, we think this morphological features are in accordance with the complicated functions of trigeminal nucleus regulating the pain sensation.