ANATOMY OF THE RAT MEDIAL GENICULATE-BODY .1. CYTOARCHITECTURE, MYELOARCHITECTURE, AND NEOCORTICAL CONNECTIVITY
ANATOMY OF THE RAT MEDIAL GENICULATE-BODY .1. CYTOARCHITECTURE, MYELOARCHITECTURE, AND NEOCORTICAL CONNECTIVITY
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DOI：
10.1002/cne.902970103
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发表时间：
1990-07-01
影响因子：
2.5
通讯作者：
COLEMAN, JR
中科院分区：
文献类型：
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作者：
CLERICI, WJ;COLEMAN, JR
对成年和幼年大鼠内侧膝状体(MGB)的细胞构筑、髓构筑和新皮质连接进行了全面的研究，以确定主要的解剖分区和核团。MGB是一个高度复杂的结构，由腹侧(MGV)、背侧(MGD)和内侧(MGM)的分区和成分核组成，每个核团都与听觉新皮质有相互联系。MGV位于中膝状束的下方，延伸至吻端，但不延伸至尾端。MGV由腹侧核和卵圆形核组成，每一区域均含有深色的中小型神经元，密集排列，呈簇状树突状形态；与MGD相反，但类似于外侧膝状体背侧核，MGV神经元的核膜在出生后早期仅为Nissl染色。将辣根过氧化物酶(HRP)注射到听皮层后，腹侧核细胞与传入臂神经轴突对齐，并以背腹方向穿透传入臂轴突，而吻尾状核细胞阵列被逆行标记。卵圆形核是一个双螺旋结构，周围环绕和穿透的传入纤维决定了构成核周膜的方向。过渡区的神经元与从卵圆形束和中膝状体束交界处发出的轴突喷雾排列在一起。边缘带神经元与游离膝状壁平行排列。MGD残留物位于中膝状束内，位于中膝状束之上，由几个染成灰白色髓鞘的细胞核组成。在未成熟材料中，MGD中的树突和胞体均按我们的方法进行Nissl染色；其中许多细胞显示出星状树枝状图案，将该区域与MGV区分开来，但类似于外侧后核未成熟神经元的染色图案。成年背侧核有中等大小的松散排列的神经元。深背核位于中膝状束的纤维之间，含有松散排列的圆形和纺锤形细胞；后者在成年神经元中所占比例较小，但在未成熟动物中是主要细胞类型。尾背核位于MGB的尾端，其吻侧突起位于背核上方，内含小的深色染色的多极细胞；腹外侧核突起低于MGV。膝上核和限束核在与听觉新皮质联系的基础上并入听觉丘脑；前者有中至暗染色的混合大小的细胞，后者有密集排列的细胞，呈垂直柱状排列。背侧分裂核的HRP标记细胞典型地表现为星状或簇状树突形态。MGM由发自下丘上臂的密集的有髓纤维束穿过，包括以尾部为主的非常大的“大细胞”神经元，以及中、小细胞。“巨细胞”神经元呈细长、三角形或圆形，排列疏松，排列不均匀，倾向于垂直定向；许多细胞具有稀疏的星状树突。大鼠内侧膝状体的分割和组织结构与Morest(Journal of Anatiy 98：611-630,1986)对猫的描述基本一致。本工作扩展了这一方案，它描述了听觉丘脑的基本哺乳动物计划。
The cytoarchitecture, myeloarchitecture, and neocortical connectivity of the rat medial geniculate body (MGB) were comprehensively studied in adult and immature rats to define major anatomical divisions and nuclei. The MGB is a highly intricate structure composed of the ventral (MGv), dorsal (MGd), and medial (MGm) divisions and component nuclei, each having reciprocal connections with auditory neocortex. The MGv lies inferior to the midgeniculate bundle and extends to the rostral, but not caudal MGB tip. The MGv is composed of ventral and ovoid nuclei bounded by a marginal zone, each region containing dark staining small and medium sized, densely packed neurons shown to have tufted dendritic morphology; in contrast to the MGd, but similar to the dorsal lateral geniculate nucleus, only the perikarya of MGv neurons stain for Nissl in early postnatal material. Ventral nucleus cells align with afferent brachial axons, which penetrate the nucleus in a dorsoventral direction, whereas rostrocaudal cellular arrays are retrogradely labeled after injections of horseradish peroxidase (HRP) into auditory cortex. The ovoid nucleus is a double spiraled structure encircled and penetrated by afferent fibers that determine the orientation of constituent perikarya. Neurons in the transition zone align with a spray of axons emanating from the juncture of the ovoid and midgeniculate bundles. Marginal zone neurons are oriented in parallel to the free geniculate wall. The MGd residues within and superior to the midgeniculate bundle, and is composed of several nuclei that stain palely for myelin. In immature material, both dendritic processes and somata in the MGd stain for Nissl with our protocol; many of these cells show a stellate arborization pattern that distinguishes this region from the Mgv, but is similar to the staining pattern of immature neurons of the lateral posterior nucleus. The adult dorsal nucleus has medium-sized, loosely packed neurons. The deep dorsal nucleus is situated among the fibers of the midgeniculate bundle and contains loosely packed round and fusiform cells; the latter cell type constitutes a minor proportion of the adult neuronal population but the major cell type in immature animals. The caudodorsal nucleus, which occupies the caudal tip of the MGB and rostrally courses superior to the dorsal nucleus, contains small, dark staining multipolar cells; the ventrolateral nucleus courses inferior to the MGv. The suprageniculate and limitans nuclei and included in the auditory thalamus on the basis of connections with auditory neocortex; the former has medium to dark staining mixed-sized cells, and the latter has densely packed cells which from a vertical column. HRP-labeled cells of dorsal division nuclei typically show either stellate or tufted dendritic morphologies. The MGm is traversed by dense myelinated fiber bundles emanating from the brachium of the inferior colliculus and includes very large "magnocellular" neurons, which predominate caudally, as well as medium-sized and small cells. "Magnocellular" neurons are elongate, triangular, or round, have loose, nonuniform packing, and tend to orient vertically; many of these cells ahve sparse, stellate dendritic arbors. The parcellation and constituent organization of the rat medial geniculate body is largely consistent with that described by Morest (Journal of Anatomy 98:611-630, 1986) for the cat. The present work extends this scheme, which describes the basis mammalian plan for the auditory thalamus.