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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(-αSMA)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-αSMA、抗α-横纹肌肌动蛋白(-αSCA)、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-αSMA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-αSMA的表达早于-αSCA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,-αSMA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-αSMA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-αSMA可作为心肌细胞早期分化的标志;流出道嵴内-αSMA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 investigate the expression and significance of α-SMA (-α SMA) in cardiac endocardial and efflux tract of human embryos in early stage. Methods 32 cases of C10 ~ C16 stage [Carnegie staging method, after fertilization (22 ± 1 ~ 37) d] human embryos were serially sectioned, anti-αSMA, anti- α-striated actin actin Immunohistochemical staining of heavy chain (MHC) antibody was used to observe the expression of -αSMA in myocardium and endocardial cushion during outflow tract remodeling. Results The human embryos developed from C10 to C15. The dorsal parietal periclinal wall of the pericardium continued to differentiate into cardiomyocytes and added to the distal end of the outflow tract. The expression of α-SMA in these cardiomyocytes was earlier than that of -αSCA and MHC. In C16 stage, -α SMA positive cells appeared near the cardiac outflow ridges, and adjacent cardiomyocytes protruded to connect with them. During the period from C12 to C15, -αSMA-positive cells gradually migrated into the outflow tract endocardial cushion. At the same time, the endothelium of the outflow tract turned to -αSMA positive and differentiated into mesenchymal cells. Different sources of mesenchymal cells co-participate in the formation of spiral outflow tract ridges. Conclusion-α SMA can be used as a marker of early cardiomyocyte differentiation. The -α SMA-positive cells in the outflow ridges may be partly derived from neural crest and partly endothelial cells that are differentiating into mesenchymal cells.