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目的通过小鼠胚胎腭裂模型,探讨地塞米松对不同孕期日小鼠胚胎腭突间充质细胞(embryonicpalatal mesenchymal cells,EPMs)增殖与凋亡的影响。方法选取孕鼠30只,分为实验组和对照组。实验组于11.5孕期日(gestational day,GD)腹腔注射50 mg/kg地塞米松,对照组注射等量生理盐水。获取13.5、14.5、15.5、16.5GD的胚胎284只,其中实验组196只,对照组为98只。头部石蜡包埋,标准颅颌冠状位5μm连续切片,进行HE染色和bcl-2免疫组织化学染色。形态学观察及EPMs中bcl 2阳性细胞计数、统计学分析。结果①bcl-2阳性信号呈棕褐色颗粒,存在于核膜周围及胞浆中。②实验组14.5、15.5GD EPMs阳性细胞数密度明显少于对照组(P<0.05),而16.5 GD阳性细胞数密度高于对照组(P<0.01)。③对照组15.5 GD EPMs的阳性信号最强,13.5GD EPMs的阳性信号表达较弱但广泛。结论胎鼠腭裂的发生与EPMs中bcl-2基因的低表达,EPMs凋亡水平升高有关。
Objective To investigate the effects of dexamethasone on the proliferation and apoptosis of embryonic palatal mesenchymal cells (EPMs) of different mouse embryos during pregnancy. Methods Thirty pregnant rats were selected and divided into experimental group and control group. The experimental group was injected intraperitoneally with dexamethasone (50 mg / kg) at gestational day (GD) for 11.5 days, and the control group was injected with normal saline. 284 embryos of 13.5, 14.5, 15.5 and 16.5GD were obtained, of which 196 were in the experimental group and 98 in the control group. Head paraffin embedded, the standard skull coronal 5μm serial sections, HE staining and bcl-2 immunohistochemical staining. Morphological observation and the number of bcl 2 positive cells in EPMs were statistically analyzed. Results ① The positive signal of bcl-2 was tan granules, which were found in the nucleus and cytoplasm. ② The numbers of positive cells in 14.5,15.5GD EPMs in experimental group were significantly less than those in control group (P <0.05), while the numbers of 16.5 GD positive cells in control group were higher than those in control group (P <0.01). ③ In the control group, the positive signals of GD EPMs were the strongest, while the positive signals of 13.5GD EPMs were weaker but more extensive. Conclusion The occurrence of fetal rat cleft palate is associated with the low expression of bcl-2 gene and the increase of apoptosis of EPMs in EPMs.