Ultrastructure of the circuit providing input to the crayfish lateral giant neurons.
Ultrastructure of the circuit providing input to the crayfish lateral giant neurons.
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为小龙虾外侧巨神经元提供输入的电路超微结构。
DOI：
10.1002/cne.903270209
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Krasne,FB
中科院分区：
文献类型：
--
作者：
Lee,SC;Krasne,FB
用电子显微镜观察了小龙虾侧巨逃逸反应回路的标记或其他识别的神经元，并与生理学的预期结果进行了比较。初级传入神经末梢有清晰的、约45纳米的不规则圆形突触囊泡，而感觉神经元中间末梢有稍大的、50纳米的、更严格的圆形囊泡，这允许根据解剖学标准进行初步分类。侧巨脑上的兴奋性突触，从生理学上被认为是电的，通常有一些间隙连接，但这些间隙连接几乎总是与功能未知的更突出的化学连接区并行。也可能有一类中间神经元在外侧巨神经元上制造纯化学突触。从初级传入神经到感觉中间神经元的突触，从生理学上被认为是胆碱能的，具有纯粹的化学形态。具有细长小泡的突触，类似于在其他神经元中看到的gaba能小泡，经常出现在初级传入神经末梢。这些突触为已知的传入输入的突触前抑制提供了基础。与生理学一致，这些抑制剂有时也接触初级传入事件的突触后靶点，有时也接受来自其他初级传入事件的输入。传入终端也从富含大而致密的包被囊泡的侧面接收一些输入。在侧巨人近端树突上发现的推定抑制输入为已知的复发性抑制提供了基础。然而，类似的抑制性突触有时会接受来自侧巨肌兴奋器的局部输入，也发现远端与兴奋性输入混合在一起。这为最近发现的兴奋后远端抑制性输入和强直抑制提供了基础。
Labeled or otherwise identified neurons of the crayfish lateral giant escape reaction circuit were examined electron microscopically and the findings compared to expectations from physiology. Terminals of primary afferents contained clear, approximately 45 nm, irregularly round synaptic vesicles, while sensory interneuron terminals had slightly larger, 50 nm, more strictly round vesicles, permitting tentative classification based on anatomical criteria. Excitatory synapses on the lateral giants, believed from physiology to be electrical, generally had some gap junctions, but these were almost invariably paralleled by more prominent chemical junctional regions of unknown function. There may also be a class of interneurons making purely chemical synapses on the lateral giants. Synapses from primary afferents to sensory interneurons, believed from physiology to be cholinergic, had purely chemical morphology. Synapses with narrow elongated vesicles, similar to GABAergic vesicles seen in other neurons, frequently occurred on terminals of primary afferents. These synapses provide a basis for known presynaptic inhibition of afferent input. Consistent with physiology, such inhibitors sometimes also contacted the postsynaptic targets of the primary afferents and sometimes received input from other primary afferents. Afferent terminals also received some input from profiles rich in large dense cored vesicles. Presumptive inhibitory input found on proximal dendrites of lateral giants provides a basis for known recurrent inhibition. However, similar inhibitory synapses that sometimes received local input from excitors of the lateral giants were also found distally mixed with excitatory inputs. These provide a basis for recently discovered distal inhibitory input following excitation and for tonic inhibition.