Von Bartheld Christopher S
Department of Physiology and Cell Biology, Mailstop 352, University of Nevada School of Medicine, Reno, NV 89557, USA.
Microsc Res Tech. 2004 Sep;65(1-2):13-24. doi: 10.1002/jemt.20095.
The definition of the terminal nerve has led to considerable confusion and controversy. This review analyzes the current state of knowledge as well as diverging opinions about the existence, components, and definition of terminal nerves or their components, with emphasis on lampreys and lungfishes. I will argue that the historical terminology regarding this cranial nerve embraces a definition of a terminal nerve that is compatible with its existence in all vertebrate species. This review further summarizes classical and more recent anatomical, developmental, neurochemical, and molecular evidence suggesting that a multitude of terminalis cell types, not only those expressing gonadotropin-releasing hormone, migrate various distances into the forebrain. This results in numerous morphological and neurochemically distinct phenotypes of neurons, with a continuum spanning from olfactory receptor-like neurons in the olfactory epithelium to typical large ganglion cells that accompany the classical olfactory projections. These cell bodies may lose their peripheral connections with the olfactory epithelium, and their central projections or cell bodies may enter the forebrain at several locations. Since "olfactory" marker proteins can be expressed in bona fide nervus terminalis cells, so-called extrabulbar "olfactory" projections may be a collection of disguised nervus terminalis components. If we do not allow this pleiomorphic collection of nerves to be considered within a terminal nerve framework, then the only alternative is to invent a highly species- and stage-specific, and, ultimately, thoroughly confusing nomenclature for neurons and nerve fibers that associate with the olfactory nerve and forebrain.
终末神经的定义引发了相当大的混乱和争议。本综述分析了关于终末神经或其组成部分的存在、组成和定义的当前知识状态以及不同观点，重点是七鳃鳗和肺鱼。我将论证，关于这条脑神经的历史术语包含了一个与它在所有脊椎动物物种中的存在相兼容的终末神经定义。本综述进一步总结了经典的和最新的解剖学、发育学、神经化学和分子证据，这些证据表明，多种终末细胞类型，不仅是那些表达促性腺激素释放激素的细胞类型，会向不同距离迁移到前脑。这导致了神经元在形态和神经化学上的多种不同表型，其连续体从嗅上皮中的嗅觉受体样神经元延伸到伴随经典嗅觉投射的典型大神经节细胞。这些细胞体可能会失去与嗅上皮的外周连接，并且它们的中枢投射或细胞体可能会在几个位置进入前脑。由于“嗅觉”标记蛋白可以在真正的终末神经细胞中表达，所以所谓的球外“嗅觉”投射可能是伪装的终末神经组成部分的集合。如果我们不允许将这种多形性的神经集合在终末神经框架内进行考虑，那么唯一的选择就是为与嗅神经和前脑相关的神经元和神经纤维发明一种高度物种和阶段特异性的、最终会彻底令人困惑的命名法。
