大鼠海马结构在空间辨别性学习记忆时的突触形态学观察

目的：探讨学习记忆活动是否可以引起大鼠海马结构发生突触可塑变化。方法：电子显微镜下对模型大鼠和对照大鼠的海马结构内突触复合体的形态进行了对比观察。结果：(1)模型大鼠海马CJ43区多形层内多为神经纤维，其中无髓纤维占多数，有髓纤维很少。在无髓纤维间见到形状不规则的轴突终末与周围的树突和树突棘分别形成轴—树突触和轴棘突触，后者多见。突触前膨大内充满圆形清亮、无核心的突触小泡和线粒体。突触后成分多为树突棘并在多处与突触前膜形成活性区，树突棘内见到棘器。(2)对照大鼠海马CA3区多形层内含有大量无髓纤维并见到较少的轴—树突触。该突触形状规则且活性带面积较小，突触后成分多为一个，突触小泡清亮、圆形无核心，偶见线粒体。(3)经Timm染色的两组大鼠海马CA3区多形层的超微结构特点是银颗粒仅沉积在苔藓纤维的髓鞘内和苔藓纤维的大终扣内，线粒体、树突干和树突棘内均无银颗粒。结论：正常生理活动和空间辨别性学习记忆活动均可引致大鼠海马CA3区多形层突触可塑性变化，但两者在形态上有所不同。

Morphological observation of synaptic plasticity of hippocampal formation induced by activity of spatial learning and memory

Objective:To study if plasticity of synaptic morphology in rat hippocampal formation during activity of learning and memory. Methods:Synaptic morphology were observed under electron microscope. Results: (1 )The microstructure of the orients layer in CA3 region of the hippocampus in the model animal was composed of large amount of unmyelinated fibers and fewer myelinated fibers. Among the unmelylinated fibers there were 2 kinds of synapses. One was the axon-spin synapes characterized as giant button and more postsynaptic elements and more active zones. Some postsynaptic elements protruded into the presynaptic button. Synaptic vesicles were mainly clear,spherical without nucleus and with fewer synaptic vesicles and larger capsular vesicle. There were lots of mitochondria around the synaptic complex and spine apparatus in the postsynaptic element of the axon-spine synapse, whith was charasterised by more flat bags and dense plate between bags. The other one was axon-dendrite synapse characterised by smaller and regular presynaptic button. (2)The microstructure of the oriens layer of the CA3 region of the hippocampus in the control animal was composed of lots of unmyelinated fibers and less myelinated fibers under electron microscopy. Among the unmyelinated fibers there was only one kind of the synapse characterised by smaller and regular axonal terminal button and only one of postsynaptic element. Synaptic vesicles were clear and spherical without nuclei, The pattern of the synapse was Gray II (symmetry). (3)Timm stain results showed sliver granular local around axon and gigant botton of mossy fibers and no mitocondria and dendrtic stem and spine and showed no difference between group. Conclusion: Synaptic plasticity happens at the orients layer of the CA3 region of the hippocampus in the model animals after getting spatial learning and memory.