Terashima T, Inoue K, Inoue Y, Mikoshiba K, Tsukada Y
J Comp Neurol. 1985 Feb 1;232(1):83-98. doi: 10.1002/cne.902320108.
Retrograde transport of horseradish peroxidase was used to examine the cells of origin of the callosal commissural fibers (CC neurons) in the primary motor cortex of normal and reeler mice. Quantitative analysis of the intracortical, laminar distribution, and dendritic orientation of CC neurons was performed in conjunction with qualitative observation of their morphology. For comparison, similar quantitative data were obtained for the cells of origin of the corticospinal tract (CST) of normal and reeler mice from materials described previously by Terashima et al. ('83). In the normal mouse, CC neurons are distributed in a bilaminar pattern such that the largest number of cells are located in supragranular layers II and III and in infragranular layer V. The majority of CC neurons are normal (upright) pyramids, although a few in the upper zone of layer VI are inverted pyramidal cells. In the reeler mutant, CC neurons are found in all cortical layers, but two-thirds are situated in the lower half of the cortex. On the basis of the celL shape and orientation of the apical dendrite, CC neurons of the reeler were classified into six morphological types: (1) typical pyramidal, (2) inverted pyramidal, (3) tumbled, (4) hook-shaped, (5) polymorphic, and (6) simple. The apical dendrites of the CC neurons in all layers of the cortex of the reeler mouse are randomly oriented; no direct relationship between the intracortical position of the soma and orientation of the apical dendrite was found. In contrast, CST neurons in the reeler mutant are concentrated in the outer third of the cortex, and there is a relationship between the laminar distribution of these cells and the alignment of their dendrites with respect to the pial surface: the apical dendrites of CST neurons lie in superficial layers tend to be oriented obliquely, whereas those of CST neurons in the deeper of cortex most often are oriented vertically, i.e, toward the pial surface. Quantitative analysis revealed that the relative intracortical positions of CC and CST neurons are reversed in the reeler mutant although both populations exhibited greater laminar disposition, and as a consequence, there is more intermingling of the two cell groups in the reeler than in the normal mouse. Thus, the present study suggests that the normal cytoarchitectonics of the primary motor cortex are inverted in the reeler mutant mouse.
利用辣根过氧化物酶的逆行运输来检查正常小鼠和裂脑小鼠初级运动皮层中胼胝体连合纤维的起源细胞（CC神经元）。结合CC神经元的形态学定性观察，对其在皮质内的层状分布和树突方向进行了定量分析。为了进行比较，从寺岛等人（1983年）先前描述的材料中获得了正常小鼠和裂脑小鼠皮质脊髓束（CST）起源细胞的类似定量数据。在正常小鼠中，CC神经元呈双分层模式分布，使得最大数量的细胞位于颗粒上层II和III以及颗粒下层V中。大多数CC神经元是正常（直立）的锥体神经元，尽管在VI层上部区域有一些是倒置的锥体神经元。在裂脑突变体中，CC神经元存在于所有皮质层中，但三分之二位于皮质的下半部分。根据细胞形状和顶树突的方向，将裂脑小鼠的CC神经元分为六种形态类型：（1）典型锥体神经元，（2）倒置锥体神经元，（3）翻滚型，（4）钩型，（5）多形型，（6）简单型。裂脑小鼠皮质各层中CC神经元的顶树突随机定向；未发现胞体在皮质内的位置与顶树突方向之间存在直接关系。相比之下，裂脑突变体中的CST神经元集中在皮质的外三分之一处，并且这些细胞的层状分布与其树突相对于软脑膜表面的排列之间存在关系：位于浅层的CST神经元的顶树突倾向于倾斜定向，而位于皮质较深层的CST神经元的顶树突最常垂直定向，即朝向软脑膜表面。定量分析表明，在裂脑突变体中，CC和CST神经元在皮质内的相对位置颠倒，尽管这两个群体都表现出更大的层状分布，因此，与正常小鼠相比，裂脑小鼠中这两个细胞群的混合更多。因此，本研究表明，初级运动皮层的正常细胞结构在裂脑突变小鼠中是颠倒的。
