Peters A, Kara D A
J Comp Neurol. 1985 Apr 8;234(2):218-41. doi: 10.1002/cne.902340208.
The pyramidal cells in area 17 of rat visual cortex have been examined by light microscopy using Golgi preparations and semithin plastic sections, and by electron microscopy. Pyramidal cells have cell bodies in layers II-VIa. The pyramidal cells in the lower portion of layer II/III are typical examples of this neuronal type in that they have pyramidal-shaped cell bodies, apical dendrites which ascend to layer I, and a skirt of basal dendrites. The pyramidal cells in upper layer II/III are similar in form but have shorter apical dendrites, while the most superficial pyramidal cells lack apical dendrites and instead have two or more primary dendrites that emanate from the upper surface of their somata. In layer V the pyramidal cells are of two sizes, medium and large, and both have a typical morphology, although the larger neurons have thicker apical dendrites and better-developed axon hillocks than the medium-sized pyramids. The medium-sized pyramidal cells of layer V outnumber the large ones to a ratio of 2.5:1. In layer IV a few typical medium-sized pyramidal cells are present, but the majority are small and can be regarded as star pyramids for they have dendrites radiating in all directions. No clearly identified spiny stellate cells have been encountered in layer IV. The pyramidal cells of layer VIa are also small, and most of them have apical dendrites which only ascend as far as layer IV. In addition to these varieties, both inverted and horizontally inclined pyramidal cells have been encountered. In electron micrographs it is apparent that although all of the pyramidal cells have symmetric axosomatic synapses, the frequency with which these synapses occur varies. The cell bodies of the various forms of pyramidal cells do not show a standard cytology. The medium-sized pyramidal cells of layer II/III usually have rounded nuclei, while the nuclei of the small pyramidal cells of layers IV and VIa are somewhat more irregular, and the large pyramidal cells of layer V have deeply indented nuclear envelopes. The appearance of the perikaryal cytoplasm also varies. The larger pyramidal cells have numerous mitochondria and well-developed Nissl bodies in their perikaryal cytoplasm, but the smaller cells have much-less-pronounced mitochondria and their rough endoplasmic reticulum is only organized into stacks at the bases of dendrites. Pyramidal cells account for about 87% of profiles of neuronal cell bodies with nuclei in layer II/III, 90% in layer IV, 89% in layer V, and 97% in layer VIa.
利用高尔基染色制剂和半薄塑料切片，通过光学显微镜以及电子显微镜对大鼠视皮层17区的锥体细胞进行了研究。锥体细胞的细胞体位于II - VIa层。II/III层下部的锥体细胞是这种神经元类型的典型例子，它们具有金字塔形的细胞体、向上延伸至I层的顶树突以及一层基底树突。II/III层上部的锥体细胞形态相似，但顶树突较短，而最表层的锥体细胞没有顶树突，取而代之的是从其胞体上表面发出的两个或更多初级树突。在V层，锥体细胞有两种大小，中型和大型，两者都具有典型的形态，尽管较大的神经元比较小的锥体神经元具有更粗的顶树突和更发达的轴丘。V层中型锥体细胞的数量是大型锥体细胞的2.5倍。在IV层存在一些典型的中型锥体细胞，但大多数是小型的，可以被视为星形锥体，因为它们的树突向各个方向辐射。在IV层未遇到明确鉴定的棘状星形细胞。VIa层的锥体细胞也很小，它们中的大多数顶树突仅向上延伸至IV层。除了这些类型外，还遇到了倒置和水平倾斜的锥体细胞。在电子显微镜照片中很明显，尽管所有锥体细胞都有对称的轴体突触，但这些突触出现的频率各不相同。各种形式锥体细胞的细胞体没有显示出标准的细胞学特征。II/III层的中型锥体细胞通常有圆形的细胞核，而IV层和VIa层的小型锥体细胞的细胞核则有些更不规则，V层的大型锥体细胞有深深凹陷的核膜。核周细胞质的外观也有所不同。较大的锥体细胞在其核周细胞质中有许多线粒体和发达的尼氏体，但较小的细胞线粒体不太明显，其粗面内质网仅在树突基部形成堆叠。锥体细胞在II/III层中占具有细胞核的神经元细胞体轮廓的约87%，在IV层中占90%，在V层中占89%，在VIa层中占97%。
