PATTERNS OF SYNAPTIC INPUT ON CORTICOCORTICAL AND CORTICOTHALAMIC CELLS IN THE CAT VISUAL-CORTEX .2. THE AXON INITIAL SEGMENT
PATTERNS OF SYNAPTIC INPUT ON CORTICOCORTICAL AND CORTICOTHALAMIC CELLS IN THE CAT VISUAL-CORTEX .2. THE AXON INITIAL SEGMENT
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DOI：
10.1002/cne.903040106
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发表时间：
1991-02-01
影响因子：
2.5
通讯作者：
DEFELIPE, J
中科院分区：
文献类型：
--
作者：
FARINAS, I;DEFELIPE, J
在本研究中，我们研究了三组逆行标记的锥体细胞的轴突起始节(AISS)的突触学特征，这些细胞是：胼胝体、皮质丘脑和同侧皮质投射细胞。这些细胞被注射到对侧视皮层、同侧外侧膝状体或同侧大脑半球19区的辣根过氧化物酶标记。这些细胞的AISS是根据连续电子显微镜的痕迹完全重建的，并确定了在其上终止的突触的数量和类型。这些数据与文献(Farinas和DeFelipe，J Comp Neurol 1991；304：53-69)中所描述的数据进行了比较，在该论文中，观察了穹窿细胞和皮质丘脑细胞体细胞的超微结构和突触。综上所述，这些数据使得我们可以对同一细胞的躯体和轴突神经支配进行比较。我们的结果显示，每个被检查的传出细胞群体都收到了一个特征和相当均匀的轴突突触数量(与轴体突触的数量相比)：16到23个轴突细胞，22到28个同侧皮质细胞，1到5个皮质丘脑细胞。由于大多数轴索性突触可能是GABA能的，因此我们得出结论，每一类锥体细胞都有不同的GABA能抑制性突触。
In the present study we examined the synaptology of the axon initial segments (AISs) of three populations of retrogradely labeled pyramidal cells: callosal, corticothalamic, and ipsilateral corticocortical projecting cells. The cells were labeled by horseradish peroxidase injected into the contralateral visual cortex, the ipsilateral lateral geniculate nucleus, or area 19 of the ipsilateral hemisphere. The AISs of these cells were completely reconstructed from tracings of serial electron micrographs and the number and type of synapses ending on them determined. These data were compared with that described in the companion paper (Farinas and DeFelipe, J Comp Neurol 1991; 304:53-69), in which the ultrastructure and synaptology of the somata of callosal and corticothalamic cells was investigated. Together, these data permit comparisons to be made between the somatic and axonic innervation of the same cells.Our results show that each population of efferent cells examined received a characteristic and rather homogeneous number (in comparison with the number of axosomatic synapses) of axoaxonic synapses: 16 to 23 for AISs of callosal cells, 22 to 28 for ipsilateral corticocortical cells, and 1 to 5 for corticothalamic cells. Since most axoxonic synapses are likely to be GABAergic, it is concluded that each population of pyramidal cells receives a distinct GABAergic inhibitory synaptic profile.