MacDonnell M F
Department of Biological Sciences, Rutgers University, New Brunswick, N.J.
Brain Behav Evol. 1989;34(4):201-11. doi: 10.1159/000116506.
A sub/supraependymal system of varicose axons in the tectal midline ridge formation of shark brains is described. Lengths of axons and their terminals are seen freestanding in the cerebrospinal fluid (CSF) as well as in close contiguity with the large CSF-contacting and supraependymal mesencephalic trigeminal neurons of the midline ridge formation. The relationship of axonal varicosities and terminals to both CSF and supraependymal somata is such as to suggest a nonsynaptic association. This finding is discussed in the context of its utility in testing the concept of parasynaptic modulation in vertebrate brains. The topographical arrangement described is one in which the essential operational elements of parasynaptic activity can be identified in a neuronal assemblage whose functional association is known.
本文描述了鲨鱼脑顶盖中线嵴形成中一个由曲张轴突组成的室管膜下/室管膜上系统。轴突及其终末的长度在脑脊液（CSF）中独立可见，也与中线嵴形成中大型接触脑脊液和室管膜上的中脑三叉神经元紧密相邻。轴突曲张和终末与脑脊液及室管膜上躯体的关系表明存在非突触联系。这一发现结合其在检验脊椎动物脑旁突触调制概念中的作用进行了讨论。所描述的拓扑排列是一种能在功能关联已知的神经元集合中识别旁突触活动基本操作元件的排列。
