皮质脑干纤维终末的超微结构——溃变电镜法研究

ULTRASTRUCTURE OF CORTICO-BRAIN STEM FIBERTERMINALS IN RATS-A DEGENERATIVEAND ELECTRON MICROSCOPIC STUDY

用溃变电镜法观察了12只大鼠的中缝大核、蓝斑、旁正中网状核、巨细胞状核、桥核、外侧网状核和下橄榄主核中皮质下行纤维终末的溃变型、超微结构及突触联系.结果如下:(1)皮质纤维有三种演变型,即电子致密型、微丝增生型和电透明型.以电子致密型为主.(2)三种溃变型在各核中出现的数量和种类不同.(3)电子致密型溃变终扣有含圆形清亮型小泡,多形清亮型小泡和混合型小泡三种终扣.各核中,三种个同小泡终扣的出现种类和数量不尽一致,以圆形清亮型小泡终扣的数量最多.(4)皮质纤维在各核中的突触联系主要是轴树突触,少量轴体突触,偶见轴轴突触.

The ultrastructure and the synaptic connections of cortical fiber terminals in the raphe mag-nus nucleus(RMV) , locus ceruleus (LC), lateral reticular nucleus (LRN), principal olivary nucleus (PDN), reticular gigantocellar nucleus (RGN), paramedian reticular nucleus (PMRN) and pontine nucleus (PN) were observed in 12 rats under electron microscope with the degenerated method. There were three kinds of degenerated changes, namely, electron density, filamentous and electron lucent degeneration. The electron dense degeneration showed different terminal types. The majority of them were the terminals containing clear round vesicles and distributed in all of 7 nuclei. A few of them were the terminals containing pleomorphic vesicles and distributed in the PN, LRN, RMN, LC, PON and RGN. Only a few of them were the terminals containing clear round and granular round vesicles and appearing in the PMRN, LC, RGN, RMN and PON. The most of degenerations in 7 nuclei were small boutons (0. 5-2. 0 μm in diameter) containing clear round vesicles. The rest of the degenerations, fewer in number, were large boutons(>2. 5 μm in diameter), the cortical fibers in the nuclei mainly formed the asymmetrical and symmetrical axo-dendrite synapsis and fewer formed axo-somatic and axo-axon synapsis. the results support the view that the connections of cortical fibers with neurons of brain stem are monosynaptic and the majority of the corticobulbar fibers are the divergent branches of the corticospinal tract.