Dalmau I, Finsen B, Tønder N, Zimmer J, González B, Castellano B
Department of Cell Biology and Physiology, Faculty of Medicine, Autonomous University of Barcelona, Bellaterra, Spain.
J Comp Neurol. 1997 Jan 6;377(1):70-84.
The distribution and appearance of microglia cell precursors in the prenatal hippocampus were examined in embryonic day 14 (E14) to E21 rats by nucleoside diphosphatase histochemistry. For comparison, the differentiation of astroglial cells was analyzed from E17 by vimentin and glial fibrillary acidic protein immunohistochemistry. Based on morphologic features, nucleoside diphosphatase-positive microglial cell precursors were classified as ameboid microglial cells and primitive ramified microglial cells. Ameboid microglia were present in the hippocampal primordium on E14. As the hippocampus developed, however, ameboid microglia gradually transformed into primitive ramified microglia, first recognized at E19. Microglial cell precursors, often related to nucleoside diphosphatase-labeled blood vessels, were particularly observed next to the pial surface on days E14 and E17 and in the highly vascularized area around the hippocampal fissure from E19. Within the brain parenchyma, the microglial cell precursors tended to be located within the differentiating cell and neuropil layers rather than in the germinative zones. The late developing dentate gyrus remained almost devoid of microglial cell precursors before birth. Vimentin-positive astroglial processes with radial orientation were observed throughout the hippocampal subregions from E17. In contrast, glial fibrillary acidic protein-positive, radial processes were barely discernible in the fimbria and the dentate gyrus before E19. The results are discussed in relation to the possible interactive role of microglial cells in central nervous tissue development and histogenesis. Regarding the origin of hippocampal microglial cell precursors, the present observations support the view that these cells may well originate from different mesodermal sources depending on time and localization.
通过核苷二磷酸酶组织化学方法，在胚胎第14天（E14）至E21天的大鼠中检查了产前海马中小胶质细胞前体的分布和外观。为了进行比较，从E17开始通过波形蛋白和胶质纤维酸性蛋白免疫组织化学分析星形胶质细胞的分化。根据形态学特征，核苷二磷酸酶阳性的小胶质细胞前体被分类为阿米巴样小胶质细胞和原始分支小胶质细胞。E14时，阿米巴样小胶质细胞存在于海马原基中。然而，随着海马的发育，阿米巴样小胶质细胞逐渐转变为原始分支小胶质细胞，最早在E19时被识别。小胶质细胞前体通常与核苷二磷酸酶标记的血管相关，尤其在E14和E17时在软脑膜表面附近以及从E19开始在海马裂周围的高度血管化区域中观察到。在脑实质内，小胶质细胞前体倾向于位于分化细胞层和神经毡层内，而不是生发区。出生前，发育较晚的齿状回几乎没有小胶质细胞前体。从E17开始，在整个海马亚区域观察到具有放射状取向的波形蛋白阳性星形胶质细胞突起。相反，在E19之前，在海马伞和齿状回中几乎看不到胶质纤维酸性蛋白阳性的放射状突起。讨论了这些结果与小胶质细胞在中枢神经组织发育和组织发生中可能的相互作用的关系。关于海马小胶质细胞前体的起源，目前的观察结果支持这样的观点，即这些细胞可能根据时间和定位很好地起源于不同的中胚层来源。
