Cliffer K D, Willis W D
Marine Biomedical Institute, University of Texas Medical Branch, Galveston 77555-0843.
J Comp Neurol. 1994 Jul 1;345(1):84-93. doi: 10.1002/cne.903450106.
Cells in the spinal cord that are postsynaptic to primary afferent fibers project to the dorsal column nuclei in the postsynaptic dorsal column pathway. The projection of cells in the cervical spinal cord of monkeys to the cuneate nucleus has been reported to avoid pars rotunda of that nucleus, the part that contains the somatotopic representation of the ipsilateral hand. We used the sensitive anterograde tracer Phaseolus vulgaris leucoagglutinin to reexamine this projection. We made multiple iontophoretic injections into the cervical enlargements of three monkeys (two Macaca fascicularis and one Macaca mulatta). Control injections were made in the contralateral dorsal columns of one of these and in the dorsal roots of a fourth animal (M. fascicularis) to test for transport by fibers of passage. After 28-39 days, the animals were deeply anesthetized and perfused, and the tissue was processed for immunohistochemical detection of the label. In all cases (excluding control injections), labeled fibers and varicosities were distributed widely in the ipsilateral cuneate and external cuneate nuclei, including pars rotunda. The dorsal column nuclei ipsilateral to control injections contained no label or only very few poorly labeled fibers, indicating that labeling through fibers of passage did not contribute importantly to the results. This study indicates that the postsynaptic projection to the cuneate nucleus is widespread and includes pars rotunda. Such projections may contribute to transmission of information originating in nociceptors through the dorsal column-medial lemniscal system to the ventrobasal thalamus.
脊髓中作为初级传入纤维突触后靶的细胞，在突触后背柱通路中投射至背柱核。据报道，猴子颈髓中的细胞向楔束核的投射避开了该核的圆形部，即包含同侧手部躯体定位表征的部分。我们使用敏感的顺行示踪剂菜豆白细胞凝集素重新研究了这一投射。我们对三只猴子（两只食蟹猴和一只恒河猴）的颈膨大进行了多次离子电渗注射。在其中一只猴子的对侧背柱以及第四只动物（食蟹猴）的背根进行对照注射，以检测通过纤维束的运输情况。28 - 39天后，将动物深度麻醉并灌注，对组织进行处理以免疫组化检测标记物。在所有情况下（不包括对照注射），标记的纤维和曲张体广泛分布于同侧楔束核和外侧楔束核，包括圆形部。对照注射同侧的背柱核未发现标记或仅有极少标记不佳的纤维，表明通过纤维束的标记对结果无重要贡献。本研究表明，向楔束核的突触后投射广泛，包括圆形部。此类投射可能有助于伤害感受器发出的信息通过背柱 - 内侧丘系系统传递至腹侧基底丘脑。
