Sugisaki N, Hirata T, Naruse I, Kawakami A, Kitsukawa T, Fujisawa H
Department of Molecular Biology, Nagoya University, Japan.
J Neurobiol. 1996 Feb;29(2):127-37. doi: 10.1002/(SICI)1097-4695(199602)29:2<127::AID-NEU1>3.0.CO;2-C.
In mice, mitral cells are the major efferent neurons of the main olfactory bulb and elongate axons into a very narrow part of the telencephalon to form a fiber bundle referred to as the lateral olfactory tract (LOT). To clarify the mechanisms responsible for guidance of mitral cell axons along this particular pathway, we co-cultured mouse embryo main olfactory bulbs with the telencephalons, and analyzed the pathways taken by mitral cell axons. Ingrowth of mitral cell axons into the telencephalon was observed in those co-cultures in which the olfactory bulbs had been exactly combined to their normal pathway (the LOT position) of the telencephalon. The axons grew preferentially along the LOT position, and formed a LOT-like fiber bundle. When the olfactory bulbs were grafted at positions apart from their normal pathway, however, no mitral cell axons grew into the telencephalon. Neocortical fragments combined with the telencephalon projected fibers into the telencephalon in random directions. These results suggest that the LOT position of the telencephalon offers a guiding pathway for mitral cell axons and that guiding cues for mitral cell axons are extremely localized.
在小鼠中，二尖瓣细胞是主嗅球的主要传出神经元，其轴突延伸至端脑的一个非常狭窄的部分，形成一个被称为外侧嗅束（LOT）的纤维束。为了阐明二尖瓣细胞轴突沿这一特定路径导向的机制，我们将小鼠胚胎主嗅球与端脑进行共培养，并分析二尖瓣细胞轴突所采取的路径。在那些嗅球已精确连接到端脑正常路径（LOT位置）的共培养物中，观察到二尖瓣细胞轴突向内生长到端脑中。轴突优先沿着LOT位置生长，并形成类似LOT的纤维束。然而，当嗅球移植到远离其正常路径的位置时，没有二尖瓣细胞轴突生长到端脑中。与端脑结合的新皮质碎片将纤维随机投射到端脑中。这些结果表明，端脑的LOT位置为二尖瓣细胞轴突提供了一条导向路径，并且二尖瓣细胞轴突的导向线索极其局限。
