Developmental and comparative studies of the glial complex in white matter

用Mori和Leblond （JCN 139: 1-30,1970）的标准检查了束间胶质复合体中发育中的少突胶质细胞的超微结构。髓鞘形成的时间进程与少突胶质细胞的成熟也进行了研究。制备纤维的水平和横切面进行电镜和免疫组织化学研究。少量散在PO处的胶质母细胞经P7转化为较长的单细胞行，P7处胶质行主要由浅色少突胶质细胞组成。在P28时，中等少突胶质细胞在胶质细胞行中占主导地位。深色少突胶质细胞出现于P28，并逐渐增多，直至P60，此时被毛已接近成体，黑色少突胶质细胞密集排列。束间胶质细胞行异质性特别突出，此外，P14至P28常观察到未分类的中间型少突胶质细胞。电镜下观察到细胞有丝分裂和细胞凋亡的变化。部分凋亡胶质细胞经免疫组化证实为星形胶质细胞。观察到凋亡细胞周围的胸腺肽阳性小胶质细胞和与邻近少突胶质细胞直接接触的星形细胞过程等胶质相互作用。P10处存在有髓鞘纤维，从P10到P60，有髓鞘纤维的平均层数显著增加约3倍（p<0.01）。髓鞘纤维占全纤维的比例也从14.5% （P14）显著增加到71.5% (P60) （p<0.01）。在胶质复合体的多灶发育模式中，少突胶质细胞似乎在每个胶质复合体中连续而独立地重复有丝分裂和凋亡。我们还利用扫描电镜和共聚焦显微镜研究了轴突-胶质细胞的相互作用。通过扫描电子显微镜观察证实了中央白质中轴突和胶质过程的理论“编织”网。少

The ultrastructure of developing oligodendrocytes in the interfascicular glial complex was examined by means of the criteria of Mori and Leblond (JCN 139 : 1-30,1970). The time course of myelination as related to the maturation of the oligodendrocytes was also investigated. Horizontal and transverse sections of fimbria were prepared for both electron microscopic and immunohistochemical studies. Few scattered glioblasts at PO became transformed into longer unicellular rows by P7, and the glial rows mainly consisted of light oligodendrocytes at P7. Medium oligodendrocytes became dominant in the glial rows at P28. Dark oligodendrocytes appeared at P28 and increased until P60 when the fimbria had an almost adult form with densely packed dark oligodendrocytes. Heterogeneity of the interfascicular glial rows was particularly prominent, and in addition unclassified intermediate types of oligodendrocytes were often observed from P14 to P28. Both mitoses and apoptosis in the glial rows were con … More firmed at the electron microscope level. Some of the apoptotic glia were immunohistochemically proved to be astrocyte. Glial interactions such as Thymosin-positive microglia surrounding apoptotic cells and astrocytic processes with direct contact to adjacent oligodendrocytes were observed. Myelinated fimbrial fibers were identified at P10, and the average number of laminae of the myelinated fibers significantly increased about three times from P10 to P60 (p<0.01). The rate of myelinating fibers among the whole fibers also significantly increased from 14.5% (P14) to 71.5% (P60) (p<0.01). In the multifocal developing pattern of the glial complex, oligodendrocytes seemed to mature continuously and independently repeating mitoses and apoptosis in each glial focus. We also investigated axon-glia interactions using scanning electron microscope and confocal microscope. Theoretical 'woven' meshwork of axons and glial processes in the central white matter was confirmed by the scanning electron microscopic observation. Less