Oland L A, Tolbert L P
Arizona Research Laboratories, University of Arizona, Tuscon 85721, USA.
J Neurobiol. 1998 Jul;36(1):41-52. doi: 10.1002/(sici)1097-4695(199807)36:1<41::aid-neu4>3.0.co;2-a.
Mitral cells are the first neurons in the mammalian olfactory bulb to synapse with olfactory receptor axons during glomerulus development, and in an invertebrate, the moth Manduca sexta, mitral-like neurons overlap very early with olfactory receptor axons as they begin to form protoglomeruli. The possibility for early interaction between receptor neurons and mitral-like neurons led us to ask whether such an interaction plays an essential role in glomerulus development. In the current study in the moth, we surgically removed a major class of these mitral-like neurons before glomeruli began to form and asked: (a) Is the formation of the array of olfactory glomeruli triggered by an interaction of the first-arriving receptor axons with the dendrites of mitral-like neurons? (b) At the level of individual glomeruli, must the mitral-like dendrites be in place either to maintain receptor axons in a glomerular arrangement, or to guide later-growing dendrites of other types into the developing glomeruli? Our results indicate that even without the participation of this group of mitral-like neurons, the array of sexually isomorphic ordinary glomeruli forms and the basic substructure of individual glomeruli develops apparently normally. We conclude that the mitral-like neurons in Manduca are not essential for the formation of ordinary olfactory glomeruli during development.
在哺乳动物嗅球中，二尖瓣细胞是在肾小球发育过程中与嗅觉受体轴突形成突触的首批神经元。在一种无脊椎动物烟草天蛾中，类似二尖瓣的神经元在开始形成原肾小球时就很早与嗅觉受体轴突重叠。受体神经元与类似二尖瓣的神经元之间早期相互作用的可能性促使我们探究这种相互作用在肾小球发育中是否起关键作用。在当前对烟草天蛾的研究中，我们在肾小球开始形成之前通过手术移除了这类主要的类似二尖瓣的神经元，并提出以下问题：（a）最早到达的受体轴突与类似二尖瓣的神经元树突之间的相互作用是否触发了嗅觉肾小球阵列的形成？（b）在单个肾小球层面，类似二尖瓣的树突是否必须就位，才能将受体轴突维持在肾小球排列中，或者引导其他类型后来生长的树突进入发育中的肾小球？我们的结果表明，即使没有这群类似二尖瓣的神经元的参与，性别同构的普通肾小球阵列仍会形成，并且单个肾小球的基本亚结构显然也会正常发育。我们得出结论，烟草天蛾中的类似二尖瓣的神经元对于发育过程中普通嗅觉肾小球的形成并非必不可少。
