Mihailoff G A
Department of Anatomy, University of Mississippi Medical Center, Jackson 39216-4505.
J Comp Neurol. 1993 Apr 1;330(1):130-46. doi: 10.1002/cne.903300111.
Small iontophoretic placements of the orthogradely transported axonal tracer Phaseolus vulgaris leucoagglutinin (PHA-L) were made in portions of the basilar pontine nuclei (BPN) or nucleus reticularis tegmenti pontis (NRTP) to determine if these cell groups provide projections to the cerebellar nuclei (CN) in the rat and if so, to visualize the morphology of the axons and terminals and illustrate any topographical organization in this system. Axons that originated from BPN or NRTP neurons and contained PHA-L were visualized by an immunohistochemical procedure that involved sequential incubation of tissue sections with goat anti-PHA-L antibody, biotinylated rabbit anti-goat immunoglobulin, and a biotin-avidin-peroxidase conjugate. Following injections of PHA-L restricted to ventral and medial portions of the BPN, labeled fibers were observed in the brachium pontis, the white matter dorsal to the CN, and to a lesser extent, in the white matter of the parafloccular stalk. Labeled preterminal axons entered the CN and gave rise to beaded axons that arborized primarily within dorsal portions of the lateral, interposed, and medial cerebellar nuclei. Injections of PHA-L restricted to either lateral portions of the BPN or ventrolateral regions of NRTP produced labeled fibers in the cerebellum that most frequently involved the parafloccular stalk and ventral portions of the CN. In contrast, dorsomedial NRTP injections resulted in the presence of labeled fibers both in the dorsal cerebellar white matter and the parafloccular stalk as well as dorsal and ventral portions of the CN. With the exception of the rostral and medial territory of interpositus anterior which received very sparse input, all portions of each CN subdivision seemed to exhibit some degree of terminal labeling. The density of labeled axon terminals in the CN appeared to be somewhat greater in the NRTP-injected cases compared to BPN-injected animals. These observations indicate that in the rat, both the BPN and NRTP contain neurons whose axons distribute to the CN. It is likely that most of the axons which project to the CN are collaterals of fibers that continue into the cerebellar cortex as mossy fibers but confirmation of this point must await further investigation. In light of the extensive projections from the cerebral cortex to the BPN and NRTP, this axonal system provides the cerebral cortex with a relatively direct route of access to the CN via one synapse in the BPN or NRTP.
将正向运输的轴突示踪剂菜豆白细胞凝集素（PHA-L）进行微量离子电渗法注射到脑桥基底核（BPN）或脑桥被盖网状核（NRTP）的部分区域，以确定这些细胞群是否向大鼠的小脑核（CN）发出投射，如果是，则观察轴突和终末的形态，并阐明该系统中的任何拓扑组织。起源于BPN或NRTP神经元并含有PHA-L的轴突通过免疫组织化学方法进行观察，该方法包括将组织切片依次与山羊抗PHA-L抗体、生物素化兔抗山羊免疫球蛋白和生物素-抗生物素蛋白-过氧化物酶复合物孵育。在将PHA-L注射到BPN的腹侧和内侧部分后，在脑桥臂、CN背侧的白质中观察到标记纤维，在较小程度上，在旁绒球柄的白质中也观察到标记纤维。标记的终末前轴突进入CN，并产生有珠状的轴突，这些轴突主要在外侧、间位和内侧小脑核的背侧部分分支。将PHA-L注射到BPN的外侧部分或NRTP的腹外侧区域，在小脑中产生的标记纤维最常涉及旁绒球柄和CN的腹侧部分。相反，向NRTP背内侧注射导致在小脑背侧白质、旁绒球柄以及CN的背侧和腹侧部分均存在标记纤维。除了前间位核的嘴侧和内侧区域接受非常稀疏的输入外，每个CN亚区的所有部分似乎都表现出一定程度的终末标记。与注射BPN的动物相比，注射NRTP的情况下CN中标记轴突终末的密度似乎略高。这些观察结果表明，在大鼠中，BPN和NRTP都含有轴突分布到CN的神经元。投射到CN的大多数轴突可能是作为苔藓纤维继续进入小脑皮质的纤维的侧支，但这一点的证实必须等待进一步研究。鉴于从大脑皮质到BPN和NRTP的广泛投射，该轴突系统为大脑皮质提供了一条通过BPN或NRTP中的一个突触相对直接进入CN的途径。
