小鼠胚胎后第二生心区与心房的发育

Development of posterior second heart field and atrium in mouse embryos

目的:探讨后第二生心区isl1阳性细胞的分布规律以及小鼠胚胎心房的发育.方法:对胚龄9～15 d小鼠胚胎心石蜡切片进行α-平滑肌肌动蛋白(α-SMA)、心肌肌球蛋白重链(MHC)、isl1和Nkx2.5免疫组织化学显色.结果:胚龄9～12d,isl1阳性细胞主要聚集于咽前间充质、心包腔背侧壁的脏壁中胚层、心背系膜以及窦房结、腔静脉瓣.此期心背侧间充质突(DMP)形成,并与房室管心内膜垫、原发隔融合.在胚龄13 d,isl1阳性细胞局限于心包腔的右腔静脉壁与窦房结.胚龄13～15d,DMP与心包内腔静脉、冠状窦壁进行心肌化.结论:后第二生心区isl1阳性细胞在胚胎不同发育时期分布模式不同,参与心房的发育.DMP来源于后第二生心区,参与原发孔的封闭.DMP的心肌化是由于原发隔的心肌细胞迁移而完成.

Objective:To investigate the distribution pattern of isll positive cells in posterior second heart field and the development of the atrium in mouse embryos.Methods:Serial sections of 9 to 15-day-old mouse embryos were stained with antibodies against α-smooth muscle actin(α-SMA),myosin heavy chain(MHC),isletl and Nkx2.5 using immunohistochemistry method.Results:The isll positive cells in 9 to 12-day-old embryos were located in the pharyngeal mesenchyme,splanchnic mesoderm of the pericardial cavity dorsal wall,dorsal mesocardium,sinuatrial node and valve of the caval vein.During embryonic day(ED) 9 to ED15,dorsal mesenchymal protrusion(DMP) was formed and fused with atrioventricular cushion and septum primum.On ED13,isll positive cells were only distributed in the wall of the intrapericardial right caval vein and sinuatrial node.During ED13 to ED15,the myocardialization was observed in DMP,intraepicardial caval vein and coronary artery.Conclusion:Isll positive cells of posterior second heart field show different distribution pattern during the different development periods,and participate in the development of the atrium.DMP is derived from the posterior second heart field,and participates in the closing of foramen primum.Myocardialization of DMP is completed by myocardial cell migration of the septum primum.