Mission J P, Takahashi T, Caviness V S
Department of Neurology, Developmental Neurobiology, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Glia. 1991;4(2):138-48. doi: 10.1002/glia.440040205.
Three cell forms of astroglial lineage populate the prenatal and early postnatal murine cerebral wall. In the present review we consider the ontogeny of these cell forms with respect to histogenetic events of the perinatal period. Classic bipolar radial glial cells predominate prior to E17. The bipolar coexist with monopolar radial forms in the perinatal period. Both bipolar and monopolar radial forms coexist with multipolar astrocytes in the course of the first postnatal week and are ultimately succeeded by the multipolar cells. The shift from bipolar to monopolar radial forms is initially coincident with translocation of somata of bipolar cells from the ventricular zone to the upper intermediate zone and cortical strata. Arborization appears to occur both at the growing tips and along the shaft of the processes of both bipolar and monopolar radial cell types. As arborization continues, the processes of the monopolar radial cells come to resemble those of the multipolar astrocytes. Eventually the radial cells are fully transformed into the multipolar astrocytic forms. During this period of transition, radial processes in the cortex appear to be degenerating, suggesting that regressive processes contribute to the cytologic transformation. This sequence of transformations begins late in the period of neuronal migration and continues through the early stages of growth and differentiation in the murine cerebral cortex. The signals that induce these changes may arise from differentiating neurons within the cortex. These transformations occur at a time when radial glial fibers are no longer required as guides for neuronal migration, and the glial population assumes new roles related to the development and operation of cortical neuronal circuits.
星形胶质细胞谱系的三种细胞形态存在于产前和产后早期的小鼠脑壁中。在本综述中，我们根据围产期的组织发生事件来考虑这些细胞形态的个体发育。经典的双极放射状胶质细胞在胚胎第17天之前占主导地位。双极细胞在围产期与单极放射状细胞形态共存。在出生后的第一周内，双极和单极放射状细胞形态均与多极星形胶质细胞共存，最终被多极细胞所取代。从双极形态向单极形态的转变最初与双极细胞的胞体从脑室区向中间上层和皮质层的移位同时发生。双极和单极放射状细胞类型的突起在生长尖端和沿轴突处似乎都发生分支。随着分支的继续，单极放射状细胞的突起开始类似于多极星形胶质细胞的突起。最终，放射状细胞完全转变为多极星形胶质细胞形态。在这个转变时期，皮质中的放射状突起似乎正在退化，这表明退行性过程有助于细胞形态的转变。这一系列转变始于神经元迁移期的后期，并持续到小鼠大脑皮质生长和分化的早期阶段。诱导这些变化的信号可能来自皮质内正在分化的神经元。这些转变发生在放射状胶质纤维不再作为神经元迁移的引导时，并且胶质细胞群体承担了与皮质神经元回路的发育和运作相关的新角色。
