Altman J
J Comp Neurol. 1975 Oct 15;163(4):427-47. doi: 10.1002/cne.901630404.
The ontogeny of the spatial organization of some components of the molecular layer was investigated in cerebella sectioned systematically in the sagittal, coronal and horizontal planes. There is no discernible organization in the distribution of cells of the proliferative zone of the external germinal layer (EGL) but from birth the differentiating bipolar cells of the subproliferative zone are aligned parallel to the surface and to the long axis of the folium. While they are still in or at the base of the EGL, the bipolar cells emit long processes, the future parallel fibers. The next step is the outgrowth of a vertical process which may reach the base of the molecular layer before the granule cell nucleus becomes translocated. The idea that the cell body truly migrates through the molecular layer is not supported by the observations. Bergmann glia cells are frequently seen in Golgi material in neonates but they are probably less numerous than in older infants and their processes are not as well aligned. It is only gradually that the EGL is perforated by flial endfeet which in older infants are occasionally organized into longitudinal rows. In mature cerebella the parallel fibers are separated by thin and relatively narrow, unstained spaces which are oriented in the longitudinal plane and can be traced from the pial surface to a zone just above the layer of Purkinje cells. It is postulated that these spaces are occupied by glial palisades formed by apposed thin vertical processes to which many Bergmann glia cells contribute. The alignment of these palisades is dependent on the orientation of parallel fibers. When the parallel fibers are reoriented by X-irradiation the glial palisades become correspondingly realigned. These observation indicate that the oriented growth of parallel fibers, which follows the polarization of bipolar cells, determines the spatial organization of the glial framework of the molecular layer. They also suggest that the glial palisades mediate functions that are not primarily developmental in nature.
在矢状面、冠状面和水平面系统切片的小脑中，研究了分子层某些成分空间组织的个体发生。外颗粒层（EGL）增殖区细胞的分布没有明显的组织，但从出生起，亚增殖区正在分化的双极细胞就与表面和小叶的长轴平行排列。当它们仍在EGL内或其底部时，双极细胞发出长突起，即未来的平行纤维。下一步是垂直突起的生长，在颗粒细胞核移位之前，该突起可能到达分子层的底部。细胞体真正穿过分子层的观点未得到观察结果的支持。在新生儿的高尔基材料中经常可以看到伯格曼胶质细胞，但它们的数量可能比大龄婴儿少，而且它们的突起排列也不那么整齐。EGL只是逐渐被丝状终足穿孔，在大龄婴儿中，丝状终足偶尔会排列成纵向行。在成熟的小脑中，平行纤维被薄的、相对狭窄的、未染色的间隙隔开，这些间隙在纵向平面上定向，可以从软膜表面追踪到浦肯野细胞层上方的一个区域。据推测，这些间隙被由并列的细垂直突起形成的胶质栅栏占据，许多伯格曼胶质细胞参与其中。这些栅栏的排列取决于平行纤维的方向。当平行纤维通过X射线照射重新定向时，胶质栅栏也会相应地重新排列。这些观察结果表明，平行纤维的定向生长遵循双极细胞的极化，决定了分子层胶质框架的空间组织。它们还表明，胶质栅栏介导的功能本质上并非主要是发育性的。
