胚胎大鼠脑内神经干细胞增殖和分化特性的初步探讨

目的 观察胎鼠发育过程中脑内神经干细胞增殖、迁移和分化特点。方法 在妊娠8～10d、12～13d和15～16d的孕鼠，分别于腹膜腔内注射BrdU，妊娠17d时取其胎鼠脑组织制备切片，免疫细胞化学方法观察BrdU标记的增殖细胞密度和分布；取E13d、E15d和E17d胎鼠皮质，分离获得神经细胞并制备成滴片，免疫细胞化学方法抗nestin和抗NeuN染色，观察不同胚期胎鼠皮质神经干细胞和神经元细胞比例。结果 E8～10d时BrdU标记的细胞主要分布于脑室周围和顶叶皮质；E12～13d时BrdU标记的细胞主要分布于脑室周围、基底节区和顶叶皮质；E15～16d时BrdU标记的细胞主要分布于丘脑和颞叶皮质。E13d、E15d和E17d胎鼠皮质nestin免疫反应阳性细胞比例随胚龄增加而逐渐减少（分别为66．4％、32．1％和3．4％），NeuN免疫反应阳性细胞比例逐渐增加（分别为17．2％、35．6％和92．3％）。结论 胎鼠发育过程中脑内神经干细胞增殖并按一定模式顺序迁移至各脑区，至出生前皮质神经细胞已基本分化成熟。

Approaching to the characteristics of proliferation, migration and differentiation of neural stem cells in fetal rat brain

Objective To evaluate the characteristics of proliferation,migration and differentiation of neural stem cells in the brain of rat embryo during development.Methods The pregnant rats were divided into three groups and were injected with BrdUperitoneally during their pregnant 8-10d,12-13d and 15-16d respectively.Their fetal brains were dissected on E17d and the brains were sliced.The distribution and density of BrdU marked regenerated cells in the brain were observed with anti BrdU immunocytochemical stain.The cortices of the rat embryos on E13d,E15d and E17d were dissected respectively. The cortices obtained were dissociated into single cells and the cell pellets were made.The pellets were stained with anti nestin and anti NeuN immunocychemical stain.Then the percentage of neural stem cells and neurons in the cortices of the fetus on different embryo days was calculated.Results The BrdU marked cells in the brains of the E8-10d fetus mainly distributed in the parietal lobe and around the ventricle.The BrdU marked cells in the brains of the E12-13d fetus mainly distributed in the parietal lobe,basal ganglion and around the ventricle.The BrdU marked cells in the brains of the E15-16d fetus mainly distributed in the thalamus and temporal lobe.The percentage of the nestin immuno reactive cells in the cortices gradually decreased along with the development of the embryos on E13d,E15d and E17d(66.4%,32.1% and 3.4% respectively),while that of NeuN immuno reactive cells gradually increased(17.2%,35.6% and 92.3% respectively).Conclusion The neural stem cells in the fetal rat brain regenerate and migrate to different brain areas according to specific model.The cortical neural cells in the rat embryo have almost completed their differentiation before birth.