Ralston D D
Department of Anatomy, University of California, San Francisco 94143.
Somatosens Mot Res. 1994;11(2):101-7. doi: 10.3109/08990229409028863.
The red nucleus (RN) of the macaque monkey is divided into a rostral two-thirds, the parvicellularis (RNp), which projects to the cerebellum by way of the inferior olivary nucleus, and a caudal third, the magnocellularis (RNm), which projects to the spinal cord via the rubrospinal tract. The RNp and RNm receive afferents from two principal sources: the cerebral motor cortices and the deep cerebellar nuclei. The terminations of these two afferent projections tend to be spatially segregated on rubral neurons, in that most corticorubral afferents terminate on more distal dendrites, and those from the deep cerebellar nuclei terminate more proximally. The present electron-microscopic analysis of the cerebellar terminations in the macaque RN provides anatomical evidence for the presence of labeled afferents in both divisions of this motor nucleus, following injection of wheatgerm agglutinin conjugated to horseradish peroxidase (WGA:HRP) into the deep cerebellar nuclei and the anterograde transport of the tracer to the RN. The cerebellar terminal afferents are large; contain numerous mitochondria and primarily rounded synaptic vesicles; and form asymmetric synaptic contacts with rubral neurons. Unlike other terminals in the nucleus, they possess an electron-lucent cytoplasmic matrix and less densely packed synaptic vesicles. They are termed "large, round, pale" (LRP) terminals because of the morphological characteristics that distinguish them from other afferent terminal types found in RN. Labeled cerebellar afferents in RNp and RNm contact primarily neuronal somata, proximal dendrites emerging from the cell body, large-diameter dendrites, and the spines of rubral neurons that arise from somata and proximal dendrites.(ABSTRACT TRUNCATED AT 250 WORDS)
猕猴的红核（RN）分为前三分之二的小细胞部（RNp），它通过下橄榄核投射到小脑，以及后三分之一的大细胞部（RNm），它通过红核脊髓束投射到脊髓。RNp和RNm接收来自两个主要来源的传入纤维：大脑运动皮层和小脑深部核团。这两种传入投射的终末在红核神经元上往往在空间上是分开的，即大多数皮质红核传入纤维终止于更远端的树突，而来自小脑深部核团的传入纤维则更靠近近端终止。目前对猕猴RN中小脑终末的电子显微镜分析提供了解剖学证据，即在将与辣根过氧化物酶结合的小麦胚芽凝集素（WGA:HRP）注入小脑深部核团并将示踪剂顺行运输到RN后，该运动核的两个部分都存在标记的传入纤维。小脑终末传入纤维较大；含有大量线粒体，主要是圆形突触小泡；并与红核神经元形成不对称突触联系。与核内的其他终末不同，它们具有电子透明的细胞质基质和突触小泡排列较疏松。由于它们的形态特征与RN中发现的其他传入终末类型不同，它们被称为“大、圆、淡”（LRP）终末。RNp和RNm中的标记小脑传入纤维主要与神经元胞体、从胞体发出的近端树突、大直径树突以及从胞体和近端树突产生的红核神经元的棘突相接触。（摘要截短于250字）
