α-平滑肌肌动蛋白在人胚心流出道早期发育中的表达

Expression of α-smooth muscle actin in the early development of the outflow tract of the human embryonic heart

目的探讨人胚早期心流出道心肌和流出道心内膜垫内α-平滑肌肌动蛋白（α-SMA）的表达规律及其意义。方法32例C10-C16期[Carnegie分期法,受精后（22±1-37）d]人胚心连续切片,经抗α-SMA、抗α-横纹肌肌动蛋白（α-SCA）、抗肌球蛋白重链（MHC）抗体免疫组织化学染色,观察流出道重塑过程中α-SMA在心肌与心内膜垫内的表达规律。结果人胚发育C10-C15期,心包腔背侧脏壁上皮不断分化为心肌细胞添加至流出道远端,这些心肌细胞α-SMA的表达早于α-SCA和MHC。C16期,流出道嵴近心肌处出现-αSMA强阳性细胞,相邻的心肌细胞伸出突起与其相连。C12-C15期,α-SMA阳性细胞逐渐迁入流出道心内膜垫内,同时可见流出道内皮转为α-SMA阳性,向间充质细胞分化。不同来源的间充质细胞共同参与形成螺旋状流出道嵴。结论α-SMA可作为心肌细胞早期分化的标志;流出道嵴内α-SMA阳性细胞可能部分来自神经嵴,部分为正在向间充质细胞分化的内皮细胞。

Objective To explore the expression pattern and significance of the α-smooth muscle actin （α-SMA） in the myoeardium and endocardial cushion of the outflow tract in the early human embryonic heart. Methods Serial sections of thirty- two human embryonic hearts from Carnegie stage 10 to Carnegie stage 16 were stained immunohistoehemieally with antibodies against α-SMA, α-sarcomerie aetin （α-SCA） and myosin heavy chain （ MHC ） to observe the α-SMA expression pattern in the myocardium and endocardial cushion during the remodeling of the outflow tract. Results During C10 to C15, the new eardiomyocytes differentiating from the pericardial splanehnie epithelium were added to the distal pole of the outflow tract. The expression of α-SMA of these cells was earlier than the expression of α-SCA and MHC. At C16, α-SMA positive cells were observed in the ridges neighboring with the myocardial cells of the outflow tract wall. The latter linked with these α-SMA positive cells by their protrusion. From C12 to C15, α-SMA positive ceils gradually migrated into the endoeardial cushion. At the same time, the endothelial cells of the outflow tract began to express α-SMA and differentiated toward mesenehymal ceils. Mesenchymal cells of different origins aggregated to form two opposite spiral ridges. Conclusion α-SMA could be regarded as an early marker of eardiomyocytes differentiation, α-SMA positive cells in the outflow tract ridges may be partly derived from the neural crest and the other part of these cells are the endothelial cells differentiating to mesenchymal cells.