Differing contributions of the first and second pharyngeal arches to tympanic membrane formation in the mouse and chick
Differing contributions of the first and second pharyngeal arches to tympanic membrane formation in the mouse and chick
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DOI：
10.1242/dev.149765
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发表时间：
2017-09-15
期刊：
影响因子：
4.6
通讯作者：
Iseki, Sachiko
中科院分区：
文献类型：
--
作者：
Furutera, Toshiko;Takechi, Masaki;Iseki, Sachiko
我们提出鼓膜（TM）的独立起源，由外耳道（EAM）和第一咽袋组成，在羊膜进化过程中，就咽弓的背腹模式而言，与独特的中耳结构有关。然而，先前的研究表明，第一咽弓（PA1）在小鼠和小鸡的TM形成中都是至关重要的。在本研究中，我们使用Hoxa2表达作为第二咽弓（PA2）的标记物，比较了这些动物沿前后轴形成的TM。在雏鸡中，EAM在PA2的外胚层表面开始内陷，而不是在第一次咽裂处，整个TM在PA2形成。失去PA2和复制PA1的鸡-鹌鹑嵌合体表明，TM的形成是通过部分EAM与PA2中的耳小柱的发育相互作用实现的，PA1也有助于EAM其余部分的形成。相比之下，在小鼠中，TM的形成与PA1中EAM和鼓室环之间的相互依赖关系高度相关。
We have proposed that independent origins of the tympanic membrane (TM), consisting of the external auditory meatus (EAM) and first pharyngeal pouch, are linked with distinctive middle ear structures in terms of dorsal-ventral patterning of the pharyngeal arches during amniote evolution. However, previous studies have suggested that the first pharyngeal arch (PA1) is crucial for TM formation in both mouse and chick. In this study, we compare TM formation along the anterior-posterior axis in these animals using Hoxa2 expression as a marker of the second pharyngeal arch (PA2). In chick, the EAM begins to invaginate at the surface ectoderm of PA2, not at the first pharyngeal cleft, and the entire TM forms in PA2. Chick-quail chimera that have lost PA2 and duplicated PA1 suggest that TM formation is achieved by developmental interaction between a portion of the EAM and the columella auris in PA2, and that PA1 also contributes to formation of the remaining part of the EAM. By contrast, in mouse, TM formation is highly associated with an interdependent relationship between the EAM and tympanic ring in PA1.