Ogata K, Kosaka T
Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan.
Neuroscience. 2002;113(1):221-33. doi: 10.1016/s0306-4522(02)00041-6.
We revealed the structural features of astrocytes by means of light microscopy, confocal laser scanning microscopy and high voltage electron microscopy, and estimated their numerical densities in the mouse hippocampus. The high voltage electron microscope examinations of Golgi-impregnated astrocytes clearly disclosed their fine leaflet-like processes in the masses occupied by individual astrocytes. The intracellular injection of two different fluorescent tracers into two neighboring astrocytes revealed that each astrocyte occupied a discrete area with a limited overlap only at its peripheral portion. In a quantitative analysis using an optical dissector, the numerical densities of astrocytes identified as S100-immunoreactive cells were only slightly different in their areal and laminar distributions. The numerical densities were higher in the stratum lacunosum-moleculare and dentate hilus, while they were slightly lower in the principal cell layers than the average (24.2 x 10(3) mm(-3)) in whole hippocampal regions. As for the dorsoventral difference, the numerical densities were significantly larger at the ventral level in the dentate gyrus, whereas such tendency was not apparent in the hippocampus proper. The projection area of the astrocytes estimated from Golgi-impregnated samples was roughly in inverse relation to the numerical densities; the areas in the stratum lacunosum-moleculare were somewhat smaller than the other layers, where the numerical densities were high. The present study indicates that astrocytes are distributed rather evenly without any prominent areal or laminar differences and that the individual astrocytes have their own domains; the periphery of the domain of a given astrocyte is interdigitated intricately with the processes of adjacent astrocytes whereas its inner core portion is not penetrated by them.
我们通过光学显微镜、共聚焦激光扫描显微镜和高压电子显微镜揭示了星形胶质细胞的结构特征，并估计了它们在小鼠海马体中的数量密度。对高尔基染色的星形胶质细胞进行的高压电子显微镜检查清楚地揭示了它们在单个星形胶质细胞占据的区域内的细叶状突起。将两种不同的荧光示踪剂细胞内注射到两个相邻的星形胶质细胞中，结果显示每个星形胶质细胞占据一个离散区域，仅在其周边部分有有限的重叠。在使用光学分割器进行的定量分析中，被鉴定为S100免疫反应性细胞的星形胶质细胞的数量密度在其面积和层状分布上仅有轻微差异。在分子层和齿状回门中的数量密度较高，而在主要细胞层中则略低于整个海马区域的平均值（24.2×10³/mm³）。至于背腹差异，齿状回腹侧水平的数量密度明显更大，而在海马体本身中这种趋势并不明显。从高尔基染色样本估计的星形胶质细胞的投射面积与数量密度大致呈反比关系；分子层中的面积略小于其他数量密度较高的层。本研究表明，星形胶质细胞分布相当均匀，没有任何明显的面积或层状差异，并且单个星形胶质细胞有其自己的区域；给定星形胶质细胞区域的周边与相邻星形胶质细胞的突起错综复杂地相互交错，而其内核部分则不会被它们穿透。
