目的 观察转录因子胰岛素增强子结合蛋白1（ISL1）在小鼠胚胎心的表达与心、第二生心区及前肠内胚层的发育。 方法 胚龄8～13d小鼠胚胎心共18个，连续石蜡切片，用抗心肌肌球蛋白重链（MHC）、抗ISL1、抗增殖细胞核抗原（PCNA）和抗α-平滑肌肌动蛋白(α-SMA)抗体进行免疫组织化学染色、免疫荧光染色和Western blotting检测。 结果 胚龄9d，ISL1阳性心前体细胞进入流出道远端。胚龄10d，ISL1阳性细胞延伸入流出道近端及静脉窦心肌。胚龄11～12d，心内ISL1表达量逐渐增多并达高峰，动脉端ISL1阳性细胞分布于流出道远端壁、心包内主肺动脉壁及主肺动脉隔，静脉端ISL1阳性细胞主要限于窦房结和静脉瓣。动脉端前肠内胚层细胞索增至最长，周围前生心区ISL1阳性细胞密度也达高峰，并且明显多于后生心区。胚龄13d，心内及第二生心区ISL1阳性细胞显著减少，内胚层细胞索趋于消失。 结论 ISL1阳性细胞在小鼠胚胎心的表达主要集中在胚龄9～13d，其表达模式与第二生心区及前肠内胚层的发育密切相关。

Objective To observe the expression patterns of islet-1(ISL1) in developing mouse embryonic hearts and the morphogenesis of the heart, the second heart field and foregut endoderm. Methods Serial sections of eighteen mouse embryonic hearts from embryonic day(ED) 8 to ED 13 were stained immunofluorescently or immunohistochemically with antibodies against myosin heavy chain(MHC), ISL1, proliferating cell nuclear antigen(PCNA) and α-smooth muscle actin(α-SMA). Expression of ISL1 was measured with Western blotting in mouse embryonic hearts from ED11 to ED14. Results At ED9, ISL1-expressing cardiac progenitors was detected at the distal wall of the outflow tract (OFT). At ED 10, ISL1 positive cells extended into the proximal wall of OFT from the distal and distributed in the myocardium of venous sinus. From ED11 to ED12, ISL1-expression reached the highest level in embryonic hearts. ISL1 positive cells were mainly distributed at the sinus node and the venous valves on venous pole of the heart but were detected at the distal wall of OFT, the developing intrapericardial aorta, pulmonary trunk and aortic-pulmonary septum on the arterial pole of the heart. At the same time, the length of solid corn stretching out from foregut endoderm reached the longest and was surrounded by ISL1-expressing progenitors of anterior component of the second heart field (aSHF). The density of ISL1 positive cells in aSHF was significantly higher than that of posterior component of the SHF. At ED13, ISL1-expressing progenitors were dramatically reduced both in the heart and the SHF, while the solid endoderm cord was gradually eliminated. Conclusion ISL1 positive progenitor cells are mainly detected from ED9 to ED13 in mouse embryonic hearts. The extent of ISL1 positive cells distribution in mouse embryonic hears is accompanied by the morphogenesis of the SHF and foregut endoderm.