Furutera Toshiko, Takechi Masaki, Kitazawa Taro, Takei Junko, Yamada Takahiko, Vu Hoang Tri, Rijli Filippo M, Kurihara Hiroki, Kuratani Shigeru, Iseki Sachiko
Section of Molecular Craniofacial Embryology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
Section of Molecular Craniofacial Embryology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
Development. 2017 Sep 15;144(18):3315-3324. doi: 10.1242/dev.149765. Epub 2017 Aug 14.
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 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.
我们提出，鼓膜（TM）的独立起源，由外耳道（EAM）和第一咽囊组成，在羊膜动物进化过程中，就咽弓的背腹模式而言，与独特的中耳结构相关联。然而，先前的研究表明，第一咽弓（PA1）对小鼠和鸡的TM形成至关重要。在本研究中，我们以第二咽弓（PA2）的表达作为标志物，比较这些动物沿前后轴的TM形成情况。在鸡中，EAM开始在PA2的表面外胚层内陷，而不是在第一咽裂，并且整个TM在PA2中形成。失去PA2并复制PA1的鸡 - 鹌鹑嵌合体表明，TM形成是通过PA2中一部分EAM与耳柱骨之间的发育相互作用实现的，并且PA1也有助于EAM其余部分的形成。相比之下，在小鼠中，TM形成与PA1中EAM和鼓膜环之间的相互依存关系高度相关。
