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目的探讨小鼠胚胎心流出道分隔过程中,前肠呼吸内胚层与咽前第二生心区细胞发育的形态学关系及机制。方法胚龄9~13d小鼠胚胎标本各6例,连续石蜡切片,用抗转录因子叉头框蛋白A2(Foxa2)、抗胰岛因子1(ISL-1)、抗patched1(Ptc1)、抗patched 2(Ptc2)、抗α-平滑肌肌动蛋白(α-SMA)及抗心肌肌球蛋白重链(MHC)抗体进行免疫组织化学及免疫荧光染色。结果胚龄9~9.5d,前肠腹侧壁ISL-1阳性内胚层局部增厚,呼吸内胚层开始发育,ISL-1阳性间充质细胞紧随其后开始出现在呼吸内胚层周围的基质中。胚龄10~11.5d,呼吸内胚层向动脉囊方向生长延伸向喉-气管沟演变,ISL-1阳性咽前间充质细胞围绕呼吸内胚层呈对称的特征性锥体形结构分布,锥体顶端突入动脉囊腔向主-肺动脉隔发育。在喉-气管沟发育过程中,总能观察到1条实心内胚层细胞索位于其腹侧顶端,Ptc1和Ptc2主要局限于发育中的喉-气管沟及实心细胞索表达,喉-气管沟及实心细胞索的内胚层则位于锥体结构的中心。胚龄12~13d,在流出道水平前肠分隔形成气管,内胚层细胞索逐渐消失,气管上皮逐渐失去Ptc1和Ptc2表达,气管腹侧的ISL-1阳性间充质细胞密度明显减低,并逐渐停止向流出道添加,动脉囊分隔完成。结论呼吸内胚层的分化发育与咽前ISL-1阳性第二生心区细胞的发育聚集密切耦联。音猬因子(SHH)信号系统在呼吸内胚层发育过程中活跃程度较高,发育中的呼吸内胚层可能作为组织中心,通过SHH信号通路诱导ISL-1阳性细胞的聚集,并通过内胚层生长延伸造成的机械牵拉力驱动ISL-1阳性细胞迁移,参与流出道正常形态发生。
Objective To investigate the morphological relationship and mechanism of foregut respiratory endoderm and cytoplasmic development in second prenatal heart area during the process of mouse cardiac abortion. Methods Six embryos from 9 to 13 days embryos were stained with continuous paraffin sections and stained with anti-patched 2 (anti-patched 2, anti-patched 1 (ISL-1) (Ptc2), anti-α-SMA and anti-MHC antibodies by immunohistochemistry and immunofluorescence staining. RESULTS: After 9-9.5 days of embryo age, the ISL-1 positive endoderm became thicker locally and the respiratory endoderm began to develop. ISL-1 positive mesenchymal cells began to appear in the stroma around respiratory endoderm in. From 10 to 11.5 days of embryo age, the respiratory endoderm extends to the laryngeal-tracheal groove in the direction of the arterial sac. ISL-1 positive pharyngeal mesenchymal cells are characterized by symmetrical pyramidal structures around respiratory endoderm. Into the arterial cysts to the main - pulmonary septal development. During the development of the larynx-trachea, one solid endoderm cell line could always be observed at the ventral tip. Ptc1 and Ptc2 were mainly confined to the developing laryngeal-tracheal groove and solid cell line, and the laryngeal-tracheal groove and The solid cell cord endoderm is located in the center of the cone structure. The embryo age ranged from 12 to 13 days. The trachea separated from the anterior intestine at the level of outflow tract. The endodermal cell line gradually disappeared. The expression of Ptc1 and Ptc2 in the tracheal epithelium gradually disappeared. The density of ISL-1 positive mesenchymal cells in the ventral trachea decreased significantly Stop adding to outflow tract, arterial sac separation completed. Conclusions The differentiation and development of respiratory endoderm are closely coupled with the development and aggregation of cells in ISL-1-positive second-heart area. The sonic hedgehog signaling (SHH) signaling system is more active during respiratory endoderm development. The developing respiratory endoderm may act as a tissue center, inducing the aggregation of ISL-1-positive cells via the SHH signaling pathway and extending through endodermal growth The resulting mechanical pull force drives the migration of ISL-1 positive cells and participates in the normal morphology of the outflow tract.