Nakajima J, Saito N, Kani K, Maeda T
Department of Ophthalmology, Shiga University of Medical Science, Japan.
Brain Res Bull. 1996;40(3):209-17. doi: 10.1016/0361-9230(96)00009-3.
The retino-collicular neuron terminals containing type A monoamine oxidase (MAO-A) in the stratum griseum superficiale of the rat superior colliculus were analyzed to provide a morphologic basis for the physiologic role of these neurons in the visual pathway. A computer-assisted, three-dimensional reconstruction of the terminal complex associated with the MAO-A-positive terminals was performed. MAO-A-positive terminals originated in the retina and terminated in the stratum griseum superficiale. This was confirmed by tract tracing and enucleation experiments. The terminals were densely grouped in clusters of irregularly shaped swellings. Electron microscopy revealed that the MAO-A-positive terminals were located in a glomerulus-like structure. In this terminal complex, a significant proportion of the axonal profiles (42.96%) synapsed with the MAO-A-positive terminals. Most of the profiles (24.16%) resembled presynaptic dendrites, which represent intermediate elements between the retinal terminals and conventional dendrites. Unlike the glomerulus in the dorsal lateral geniculate body, the MAO-A-positive terminal swellings were not located in the central part of the terminal complex. The terminals had an irregular shape and were located in the complex. The terminal complex was partially ensheathed by glial processes. Furthermore, the membrane surfaces exhibiting synaptic specializations were very small compared with the total surface of the terminal swellings. The membrane length of the synaptic specialization was 5.38% of the total perimeter of the MAO-A-positive terminals.
对大鼠上丘浅层中含有A型单胺氧化酶（MAO-A）的视网膜-丘脑神经元终末进行分析，为这些神经元在视觉通路中的生理作用提供形态学依据。对与MAO-A阳性终末相关的终末复合体进行了计算机辅助三维重建。MAO-A阳性终末起源于视网膜，终止于上丘浅层。束路追踪和眼球摘除实验证实了这一点。这些终末密集地聚集成形状不规则的膨大簇。电子显微镜显示，MAO-A阳性终末位于类似小球的结构中。在这个终末复合体中，相当一部分轴突轮廓（42.96%）与MAO-A阳性终末形成突触。大多数轮廓（24.16%）类似于突触前树突，它们代表视网膜终末和传统树突之间的中间成分。与背侧外侧膝状体中的小球不同，MAO-A阳性终末膨大并不位于终末复合体的中央部分。这些终末形状不规则，位于复合体中。终末复合体部分被神经胶质突起包裹。此外，与终末膨大的总表面积相比，呈现突触特化的膜表面非常小。突触特化的膜长度占MAO-A阳性终末总周长的5.38%。
