Cuadros M A, Navascués J
Departamento de Biología Celular, Facultad de Ciencias, Universidad de Granada, Spain.
Prog Neurobiol. 1998 Oct;56(2):173-89. doi: 10.1016/s0301-0082(98)00035-5.
Some authors claim that microglia originate from the neuroepithelium, although most now believe that microglial cells are of mesodermal origin, and probably belong to the monocyte/macrophage cell line. These cells must enter the developing central nervous system (CNS) from the blood stream, the ventricular space or the meninges. Afterward microglial cells are distributed more or less homogeneously through the entire nervous parenchyma. Stereotyped patterns of migration have been recognized during development, in which long-distance tangential migration precedes radial migration of individual cells. Microglial cells moving through the nervous parenchyma are ameboid microglia, which apparently differentiate into ramified microglia after reaching their definitive location. This is supported by the presence of cells showing intermediate features between those of ameboid and ramified microglia. The factors that control the invasion of the nervous parenchyma, migration within the developing CNS and differentiation of microglial cells are not well known. These phenomena apparently depend on environmental factors such as soluble or cell-surface bound molecules and components of the extracellular matrix. Microglial cells within the developing CNS are involved in clearing cell debris and withdrawing misdirected or transitory axons, and presumably support cell survival and neurite growth.
一些作者声称小胶质细胞起源于神经上皮，尽管现在大多数人认为小胶质细胞起源于中胚层，并且可能属于单核细胞/巨噬细胞系。这些细胞必须从血流、脑室腔或脑膜进入发育中的中枢神经系统（CNS）。之后，小胶质细胞或多或少均匀地分布在整个神经实质中。在发育过程中已经识别出刻板的迁移模式，其中单个细胞的长距离切向迁移先于径向迁移。穿过神经实质的小胶质细胞是阿米巴样小胶质细胞，它们显然在到达最终位置后分化为分支状小胶质细胞。这得到了显示阿米巴样和分支状小胶质细胞之间中间特征的细胞存在的支持。控制神经实质侵袭、在发育中的中枢神经系统内迁移以及小胶质细胞分化的因素尚不清楚。这些现象显然取决于环境因素，如可溶性或细胞表面结合分子以及细胞外基质的成分。发育中的中枢神经系统内的小胶质细胞参与清除细胞碎片和撤回错误导向或短暂的轴突，并可能支持细胞存活和神经突生长。
