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目的 :探讨SD大鼠外胚间充质干细胞的超微结构及经体外长期传代后变化程度。方法 :电镜分析组织细胞的超微结构 ;用流式细胞仪检测传代细胞的干细胞特异性标志CD57和P75的变化。结果 :细胞增殖旺盛 ,代谢活跃 ,处于未分化状态。P0 -P5期间 ,CD57和P75阳性细胞的比例没有明显降低 ,从P6开始 ,下降迅速 ,至P8-P10 期间已不可测。结论 :①干细胞可以在体外维持生长并增殖 ;②长期培养后 ,干细胞比例下降 ,甚至消失 ,这可能存在两种原因 :其一 ,干细胞经过体外培养已经完全分化了 ,失去了原有的表型 ;其二 :干细胞仍然存在 ,但缓慢增殖 ,被增殖迅速的瞬时扩增细胞稀释 ,以至无法检测
OBJECTIVE: To investigate the ultrastructure of ectomesenchymal stem cells in SD rats and their changes after long-term passage in vitro. Methods: The ultrastructure of tissue cells was analyzed by electron microscopy. The changes of stem cell specific markers CD57 and P75 in subcultured cells were detected by flow cytometry. Results: The cells proliferated vigorously and were metabolically active and in an undifferentiated state. During P0-P5, there was no significant decrease in the proportion of CD57- and P75-positive cells, beginning with P6, declining rapidly and not measurable by P8-P10. Conclusion: ①Stem cells can maintain growth and proliferation in vitro; ② After long-term culture, the proportion of stem cells decreased or disappeared, which may exist for two reasons: First, stem cells have been completely differentiated in vitro and lost the original phenotype ; Second: Stem cells are still present but proliferate slowly, are diluted by rapidly proliferating transiently expanded cells and can not be detected