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目的探讨小鼠胚胎心脏工作心肌和传导系心肌在形态发生和分化过程中核纤层蛋白A(lamin A)、转录因子TBX3、缝隙连接蛋白43(Cx43)的表达特点。方法用抗α-平滑肌肌动蛋白(α-SMA)、抗心肌肌球蛋白重链(MHC)、抗α-横纹肌肌动蛋白(α-SCA)、抗胰岛因子1(ISL-1)、抗Cx43、抗lamin A和抗转录因子TBX3,对46只胚龄8~15d小鼠胚胎心脏连续石蜡切片进行免疫组织化学及免疫荧光染色。结果胚龄9d,TBX3在原始心管的表达集中在房室管壁。10d始,TBX3阳性的表达逐渐从房室管壁沿着静脉瓣延续至窦房结、右心房背侧壁和房间隔。胚龄12~13d,TBX3阳性表达结构构成了中枢传导系雏形,包括窦房结、左右静脉瓣、房间隔、房室管、房室结和房室束。Cx43首先在胚龄9d的左心室腹侧壁和部分小梁心肌出现弱阳性表达,随着发育,Cx43逐渐在TBX3阴性的心房、心室工作心肌表达。Lamin A首先出现在10d房室管心内膜垫间充质细胞和左心室部分小梁心肌,随后在右心室小梁心肌出现,至胚龄15d,心室和心房小梁心肌及房室瓣均可见lamin A阳性表达,但致密心肌和中枢传导系心肌持续呈阴性表达。结论中枢传导系统雏形在小鼠胚龄13d形成,呈TBX3阳性,Cx43阴性的互补性表达。致密心肌和中枢传导系心肌在15d仍为lamin A表达阴性,说明此部分心肌分化成熟较晚。
Objective To investigate the expression of lamin A, transcription factor TBX3 and connexin 43 (Cx43) during the morphogenesis and differentiation of mouse embryonic heart and cardiac myocytes. Methods The anti-α-SMA, anti-MHC, anti-α-SCA, ISL-1 and anti- Cx43, anti-lamin A and anti-transcription factor TBX3. Immunohistochemistry and immunofluorescence staining were performed on the continuous paraffin sections from 46 embryos of 8-15 days old embryos. Results At embryonic age 9 days, the expression of TBX3 in primary cardiac tube was concentrated in the atrioventricular wall. At 10 days, the expression of TBX3 gradually extended from the atrioventricular wall along the venous valve to the sino-atrial node, the dorsal right atrium and the septum. The embryo age 12 ~ 13d, TBX3 positive expression constitutes the shape of the central conduction line embryo, including the sinus node, left and right venous valves, atrial septal, atrioventricular canal, atrioventricular node and atrioventricular bundle. Cx43 first appeared weakly positive in the left ventricle ventral wall and some of the trabecular myocardium at embryonic day 9d. With development, Cx43 was gradually expressed in the TBX3 negative atrial and ventricular myocardium. Lamin A first appeared in 10 days atrioventricular endocardial mesenchymal cells and left ventricular part of trabecular myocardium, followed by right ventricular trabecular myocardium, to embryo age 15d, ventricular and atrial trabecular myocardium and atrioventricular valve The positive expression of lamin A was found, but the myocardium of the dense myocardium and central conduction system continued to be negative. Conclusion The central conduction system prototype formed in embryonic age 13d, showing TBX3 positive, Cx43 negative complementary expression. Myocardium in dense myocardium and central conduction system remained lamin A negative for 15 days, indicating late maturation and differentiation of this part of myocardium.