Reichenbach A, Siegel A, Senitz D, Smith T G
Carl Ludwig Institute of Physiology, Leipzig University, Germany.
Neuroimage. 1992 Aug;1(1):69-77. doi: 10.1016/1053-8119(92)90008-b.
Camera-lucida drawings of Golgi-impregnated astroglial cells and their processes are described by the fractal dimension of their borders, which is an objective, quantitative measure of morphological complexity. Protoplasmic astrocytes from human neocortex have fractal dimensions (D) that are larger than those of fibrous astrocytes from the cat optic nerve. Marginal astrocytes from monkey cerebropontile angle have two kinds of processes: (1) short, thick processes with endfeet abutting the pial surface, with relatively high D's, and (2) very long, thin processes extending into the neuronal tissue, with very low D's. These data indicate that short astrocytic processes may have a complex surface (and have a high D), whereas long processes are rather smooth (and have a low D). A comparison between transmission electron microscopy morphometry and measures of D at the light microscopic level, performed on different parts of rabbit retinal Müller glial cells, suggests that D is strongly correlated to the surface-to-volume ratio which, in part, determines the length constant of a cable for core-conductance of currents. We provide data supporting the hypothesis that astroglial cell geometry is adjusted to allow for sufficient spatial buffering K+ currents, even through very long processes.
通过其边界的分形维数来描述经高尔基染色的星形胶质细胞及其突起的明箱绘图，这是一种对形态复杂性的客观、定量测量。来自人类新皮质的原浆性星形胶质细胞的分形维数（D）大于来自猫视神经的纤维性星形胶质细胞的分形维数。来自猴脑桥小脑角的边缘星形胶质细胞有两种突起：（1）短而粗的突起，其终足邻接软脑膜表面，具有相对较高的D值；（2）非常长而细的突起，延伸到神经组织中，具有非常低的D值。这些数据表明，短的星形胶质细胞突起可能具有复杂的表面（并且具有高D值），而长突起则相当光滑（并且具有低D值）。在兔视网膜Müller胶质细胞的不同部位进行的透射电子显微镜形态测量与光镜水平的D测量之间的比较表明，D与表面体积比密切相关，表面体积比在一定程度上决定了电流核心传导电缆的长度常数。我们提供的数据支持这样的假设，即星形胶质细胞的几何形状经过调整，即使通过非常长的突起也能实现足够的空间缓冲钾离子电流。
