人胚静脉窦与心背侧间充质突的形成与重塑

Formation and remodeling of the sinus venosus and the dorsal mesenchymal protrusion in human embryo

背景:有关人胚心脏静脉窦的形成与重塑以及心背侧间充质突的功能尚存在争议。目的:探讨人胚心房分隔过程中心背侧间充质突的确切功能以及静脉窦的形成与转归。方法:收集的人胚胎立即固定24 h后,体视显微镜下依据Carnegie分期法进行分期,分为Carnegie stage10(CS10)-CS17。对人胚心脏切片进行免疫组织化学染色。结果与结论:(1)CS10-CS12,胚胎原始咽腹侧间充质与心包背侧壁的isl1阳性细胞延续至静脉窦壁参与其心肌形成;(2)自CS13始,冠状窦和腔静脉壁开始表达isl1,并逐渐有心肌细胞形成。同时,isl1阳性细胞参与心背侧间充质突形成;(3)CS15,心背侧间充质突参与心房分隔并逐渐心肌化;(4)结果表明,人胚静脉窦以及冠状窦、腔静脉壁的心肌来自于第二生心区的isl1阳性细胞的分化;人胚心背侧间充质突的形成与功能与小鼠胚胎的相似。

BACKGROUND： Formation and remodeling of sinus venosus and the function of the dorsal mesenchymal protrusion（DMP） in human embryonic heart remain controversial.OBJECTIVE： To explore the function of DMP and the sinus venosus development in the process of human embryo atrial separation. METHODS： The human embryos were fixed for 24 hours immediately after harvesting, followed by staged based on Carnegie stage（CS10-CS17） under stereo microscope. Serial sections of human embryos were stained immunohistochemically. RESULTS AND CONCLUSION： During CS10-CS12, the isl1 positive cells of the pharyngeal ventral mesenchyme and the dorsal pericardial wall extended to the sinus venosus wall to contribute to myocardium formation. From CS13, isl1 began to express in the coronary sinus and the caval vein wall and these blood vessels began to be myocardialized. Meanwhile, the isl1 positive cells participated in the formation of DMP.At CS15, the DMP contributed to the atrial separation and was myocardialized gradually. These data suggest that in human embryo, the sinus venosus is formed and the myocardium of the venous tributaries is derived from the isl1 positive cells of second heart field. The formation and function of the DMP in human embryo are similar to those of the mouse embryo.