The development and evolution of the pharyngeal arches
The development and evolution of the pharyngeal arches
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DOI：
10.1046/j.1469-7580.2001.19910133.x
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发表时间：
2001-07-01
影响因子：
2.4
通讯作者：
Graham, A
中科院分区：
文献类型：
--
作者：
Graham, A
肌肉发达的咽部有骨骼支撑，具有进食和呼吸的双重功能，是脊椎动物的基本特征。在胚胎学上，咽器起源于胚头外侧表面形成的一系列凸起，即咽弓，其发育是复杂的。这些结构由许多不同类型的胚胎细胞组成：外胚层、内胚层、神经嵴和中胚层，它们的发育必须协调才能产生功能性的成体器官。在过去，大多数研究都强调神经嵴在指导咽弓发育中所起的作用，神经嵴产生弓的骨骼元素，但也很明显，内胚层在指导咽弓发育中起着突出作用。神经嵴细胞不需要弓的形成，也不需要它们的区域化，在某种程度上也不需要它们的认同感。此外，内胚层是许多重要信号分子的主要表达部位，并且该组织已被证明负责促进拱门特定成分的形成。因此，脊椎动物咽部形态发生现在可以看作是一个比以前认为的更复杂的过程，并且必须是神经嵴和内胚层模式机制整合的结果。有趣的是，这也反映了咽节的进化起源早于神经嵴的进化起源，而神经嵴是脊椎动物独有的特征。因此，脊椎动物咽的进化也可能是这两种模式系统整合的结果。神经嵴和内胚层模式之间相互作用的改变也可能是在随后的脊椎动物进化中发生在咽区的进化的原因。
A muscularised pharynx, with skeletal support, serving the dual functions of feeding and respiration, is a fundamental vertebrate characteristic. Embryologically, the pharyngeal apparatus has its origin in a series of bulges that form on the lateral surface of the embryonic head, the pharyngeal arches, whose development is complex. These structures are composed of a number of disparate embryonic cell types: ectoderm, endoderm, neural crest and mesoderm, whose development must be coordinated to generate the functional adult apparatus. In the past, most studies have emphasised the role played by the neural crest, which generates the skeletal elements of the arches, in directing pharyngeal arch development, but it has also become apparent that the endoderm plays a prominent role in directing arch development. Neural crest cells are not required for arch formation, their regionalisation nor to some extent their sense of identity. Furthermore, the endoderm is the major site of expression of a number of important signalling molecules, and this tissue has been shown to be responsible for promoting the formation of particular components of the arches. Thus vertebrate pharyngeal morphogenesis can now be seen to be a more complex process than was previously believed, and must result from an integration of both neural crest and endodermal patterning mechanisms. Interestingly, this also mirrors the fact that the evolutionary origin of pharyngeal segmentation predates that of the neural crest, which is an exclusively vertebrate characteristic. As such, the evolution of the vertebrate pharynx is also likely to have resulted from an integration between these 2 patterning systems. Alterations in the interplay between neural crest and endodermal patterning are also likely to be responsible for the evolutionary that occurred to the pharyngeal region during subsequent vertebrate evolution.