Li Y Q, Takada M, Kaneko T, Mizuno N
Department of Morphological Brain Science, Faculty of Medicine, Kyoto University, Japan.
J Comp Neurol. 1995 Jun 12;356(4):563-79. doi: 10.1002/cne.903560407.
The distribution of premotor neurons for trigeminal motor nucleus neurons innervating the jaw-closing and jaw-opening muscles was examined in the lower brainstem of the rat by using retrograde and anterograde labeling techniques. First, Fluorogold, a fluorescent retrograde tracer, was injected into the dorsolateral or ventromedial division of the trigeminal motor nucleus, each of which contains motoneurons innervating the jaw-closing or jaw-opening muscles, respectively. Second, Phaseolus vulgaris-leucoagglutinin, an anterograde tracer, was injected into each of the lower brainstem sites, where clusters of retrogradely labeled premotor neurons had been seen in the first set of experiments. Third, after injection of the anterograde tracer into a lower brainstem site, followed by injection of the retrograde tracer cholera toxin B subunit into a masticatory muscle, termination of anterogradely labeled axons onto retrogradely labeled motoneurons was confirmed with the aid of a confocal laser-scanning microscope. It was found that the premotor neurons distributed in the mesencephalic trigeminal nucleus, medial part of the parabrachial region, supratrigeminal region, and dorsal parts of the principal sensory, oral spinal and interpolar spinal trigeminal nuclei project preferentially to the dorsolateral division of the trigeminal motor nucleus, whereas those in the lateral part of the parabrachial region, intermediate parts of the principal sensory, oral spinal and interpolar spinal trigeminal nuclei, and alpha part of the gigantocellular reticular nucleus project preferentially to the ventromedial division of the trigeminal motor nucleus. The dorsal and lateral parts of the medullary reticular formation and the medullary raphe nuclei contain premotor neurons of both types. Group k motoneurons, a cluster of trigeminal motoneurons that innervate the tensor tympani muscle, receive projection fibers predominantly from the dorsolateral part of the oral pontine reticular formation.
运用逆行和顺行标记技术，在大鼠脑干下部研究了支配闭口肌和开口肌的三叉神经运动核神经元的运动前神经元分布情况。首先，将荧光逆行示踪剂荧光金注入三叉神经运动核的背外侧或腹内侧部分，其中每一部分分别包含支配闭口肌或开口肌的运动神经元。其次，将顺行示踪剂菜豆凝集素注入在第一组实验中观察到有逆行标记运动前神经元簇的每个脑干下部位点。第三，在将顺行示踪剂注入一个脑干下部位点后，接着将逆行示踪剂霍乱毒素B亚单位注入一块咀嚼肌，借助共聚焦激光扫描显微镜确认顺行标记轴突在逆行标记运动神经元上的终末。结果发现，分布于中脑三叉神经核、臂旁区域内侧部分、三叉上区域以及主要感觉、口部脊髓和极间脊髓三叉神经核背侧部分的运动前神经元优先投射至三叉神经运动核的背外侧部分，而位于臂旁区域外侧部分、主要感觉、口部脊髓和极间脊髓三叉神经核中间部分以及巨细胞网状核α部分的运动前神经元优先投射至三叉神经运动核的腹内侧部分。延髓网状结构的背侧和外侧部分以及延髓中缝核包含这两种类型的运动前神经元。k组运动神经元是一群支配鼓膜张肌的三叉神经运动神经元，主要接受来自口桥网状结构背外侧部分的投射纤维。
