小鼠胚胎流出道心内膜α-平滑肌肌动蛋白阳性细胞的分布

Distribution of the alpha-smooth muscle actin positive cells in the outflow tract endocardium in embryonic mouse heart

背景:早期胚胎心脏流出道心内膜α-平滑肌肌动蛋白阳性细胞参与了流出道的分隔,但在流出道分隔中的分布规律及作用机制仍然不明。目的:观察心内膜α-平滑肌肌动蛋白阳性细胞在流出道分隔过程中分布的时空规律,探讨其与流出道分隔的关系。设计、时间及单位:单一样本观察,于2006-06/2007-12在山西医科大学组织胚胎学教研室完成。材料:鼠龄3个月的雌性中国昆明小鼠30只,体质量30～32g。方法:妊娠小鼠经乙醚麻醉,收集9～16d胎龄胚胎共32只,制作心脏切片。连续切片每10片取1片做苏木精-伊红染色,其余9片进行免疫组织化学染色。主要观察指标:抗α-平滑肌肌动蛋白、抗结蛋白、抗α-横纹肌肌节肌动蛋白单克隆抗体在胎龄9～16d小鼠胚胎心脏流出道的表达。结果:胎龄10d,可见α-平滑肌肌动蛋白阳性主肺动脉隔形成,同时,α-平滑肌肌动蛋白阳性细胞沿弓动脉壁迁入流出道心胶质。胎龄11d,流出道心内膜内,α-平滑肌肌动蛋白阳性和α-平滑肌肌动蛋白阴性间充质细胞聚集形成流出道嵴。胎龄12～13d,主肺动脉隔将半月瓣远端流出道分隔为升主动脉和肺动脉干,主肺动脉隔分化为升主动脉和肺动脉干相对的内侧壁。胎龄13d后,半月瓣以下,流出道嵴愈合形成流出道隔,将流出道近段分为左右心室流出道。流出道隔中可见部分α-平滑肌肌动蛋白阳性细胞聚集呈漩涡状。间充质性流出道隔形成与其肌性化相伴随。结论:流出道心内膜和主肺动脉隔的α-平滑肌肌动蛋白强阳性细胞来自神经嵴。流出道不同部位的α-平滑肌肌动蛋白阳性神经嵴细胞功能不同,与流出道其他细胞成分相互作用,完成流出道的分隔和重建。

BACKGROUND： The α-smooth muscle actin （ α-SMA） positive cells in the endocardial ridges in early embryo are involved in the septation of the outflow tract, but the distribution and mechanism of α-SMA positive cells during the septation of the outflow tract have remained unclear. OBJECTIVE： To observe the time-space distribution of the a -SMA positive cells in the endocardium during the septation of the outflow tract, and to investigate the relationship between the distribution of α-SMA positive cells and the septation of outflow tract. DESIGN, TIME AND SETTING： A single sample observational experiment was performed at the Department of Histology and Embryology, Shanxi Medical University from June 2006 to December 2007. MATERIALS： Thirty three-month old female mice of China （Kunming） species, weighing 30-32 g, were used in this study. METHODS： Under anesthesia with ethyl ether, 32 embryos from embryonic day 9 to embryonic day 16 obtained from pregnant mice. The serial sections of hearts were prepared. One section from every ten was selected for hematoxylin and eosin staining, and the other nine sections were selected for immunohistochemistry staining, MAIN OUTCOME MEASURES： The expressions of α-SMA, desmin and a -sarcomeric actin （ α-SCA） in the outflow tract of embryonic mice hearts. RESULTS： At embryonic day 10, α-SMA positive aortico-pulmonary septum was formed. At the same time, a -SMA positive cells began to migrate into the cardiac jelly of the outflow tract along the wall of arch arteries. At embryonic day 11,α-SMA positive cells and a -SMA negative cells accumulated to form two outflow tract ridges. At embryonic days 12-13, the outflow tract distal end to the semilunar valves was septated into ascending aorta and pulmonary trunk by the aorto-pulmonary septum. The aortico-pulmonary septum was developed into the facing walls of both arteries. After embryonic day 13, the two endocardial ridges at the proximal end to the semilunar valves fused to form the outlet septum to septate the proximal part of the outflow tract into the subpulmonary and subaortic outlet of the ventricles. The a -SMA positive cells accumulated to form a highly characteristic central whorl in the outlet septum. The outlet septum was gradually myocardialized accompanied by the formation of it. CONCLUSION： α-SMA positive cells in the endocardium and aorto-pulmonary septum are neural crest-derived and are of heterogeneity in function. Interaction of neural crest-derived α-SMA positive cells with the other components of the outflow tract completes the septation and remodeling of the outflow tract.