海马的树突和树－树连接的超微结构

ULTRASTRUCTURE OF THE DENDRITES AND DENDRO-DENDRITIC JUNCTIONS IN THE HIPPOCAMPUS

用电镜方法观察了大白鼠ＣＡ１区的神经组织超微结构，发现神经毯内的树突、侧棘、轴突以及神经胶质非常复杂。树突内微管显著。侧棘有不同的形态类型，有些侧棘常有小棘伸出。棘器不仅出现在侧棘内，而且在一些树突内也可遇见。某些侧棘内可见颗粒小泡或包被小泡。神经毯内广泛存在轴－树突触（圆形小泡，Ⅱ型突触），轴－棘突触（圆形小泡，Ⅰ型突触）和树－树突触（圆形小泡，Ⅲ型突触）。此外，还首次在海马内发现非突触性的树－树紧密连接，它可能是假突触，其功能意义有待进一步研究。本文提示海马树突和突触的复杂性可能对学习和记忆有着重要的作用。

Ultrastructure of the nervous tissue of the hippocampal CA1 in the rats were examined by electron microscopy. It was found that the dendrites,dendritic spines. axons and neuroglia in the hippocampal neuropil were very complicated. The microtubules in the dendrites were conspicuous. The spine profiles may be divided to several morphological types and the spinules often protruded from some dendritic spines in the hippocampalCA1. The spine apparatus was not only contained in the spines ,but alsooccasionally encountered in certain dendrites. The granular vesiclesor coated vesicles were seen in some spines. The axo-dendritic sgnapses (spheroid vesicle,type Ⅱ synapse ) ,axo-spinous synapses (spheroid vesicle , type Ⅰ synapse) and dendro -dendritic synapses ( spheroid vesicle ,type Ⅰ synapse ) were distibuted throughout the neuropil. In addition to above mentioned synapses . from present findings it was also revealed that the tight junction of the nonsynaptic dendro-dendritic contact was discovered for the first time in the hippocampal CA1 of the rat.This junction probably is a ephase and its functional significance remain to be further studied. The present results indicate that the complexity of the dendrites and synapses in the hippocampus may have an important role for the mechanism of learning and memory.