Noden Drew M, Francis-West Philippa
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Dev Dyn. 2006 May;235(5):1194-218. doi: 10.1002/dvdy.20697.
Unraveling the complex tissue interactions necessary to generate the structural and functional diversity present among craniofacial muscles is challenging. These muscles initiate their development within a mesenchymal population bounded by the brain, pharyngeal endoderm, surface ectoderm, and neural crest cells. This set of spatial relations, and in particular the segmental properties of these adjacent tissues, are unique to the head. Additionally, the lack of early epithelialization in head mesoderm necessitates strategies for generating discrete myogenic foci that may differ from those operating in the trunk. Molecular data indeed indicate dissimilar methods of regulation, yet transplantation studies suggest that some head and trunk myogenic populations are interchangeable. The first goal of this review is to present key features of these diversities, identifying and comparing tissue and molecular interactions regulating myogenesis in the head and trunk. Our second focus is on the diverse morphogenetic movements exhibited by craniofacial muscles. Precursors of tongue muscles partly mimic migrations of appendicular myoblasts, whereas myoblasts destined to form extraocular muscles condense within paraxial mesoderm, then as large cohorts they cross the mesoderm:neural crest interface en route to periocular regions. Branchial muscle precursors exhibit yet another strategy, establishing contacts with neural crest populations before branchial arch formation and maintaining these relations through subsequent stages of morphogenesis. With many of the prerequisite stepping-stones in our knowledge of craniofacial myogenesis now in place, discovering the cellular and molecular interactions necessary to initiate and sustain the differentiation and morphogenesis of these neglected craniofacial muscles is now an attainable goal.
揭示生成颅面肌肉中存在的结构和功能多样性所需的复杂组织相互作用具有挑战性。这些肌肉在由脑、咽内胚层、表面外胚层和神经嵴细胞界定的间充质群体中开始发育。这组空间关系，尤其是这些相邻组织的节段特性，是头部所特有的。此外，头部中胚层缺乏早期上皮化，这就需要有产生离散肌源性灶的策略，这些策略可能与在躯干中起作用的策略不同。分子数据确实表明调控方法不同，但移植研究表明，一些头部和躯干的肌源性群体是可互换的。本综述的第一个目标是呈现这些多样性的关键特征，识别和比较调节头部和躯干肌生成的组织和分子相互作用。我们的第二个重点是颅面肌肉所表现出的多样形态发生运动。舌肌的前体细胞部分模仿附肢成肌细胞的迁移，而注定要形成眼外肌的成肌细胞在轴旁中胚层内聚集，然后作为大群体穿过中胚层：神经嵴界面，前往眼周区域。鳃肌前体细胞表现出另一种策略，在鳃弓形成之前与神经嵴群体建立联系，并在随后的形态发生阶段维持这些关系。随着我们对颅面肌生成的许多必要基础现在已经具备，发现启动和维持这些被忽视的颅面肌肉的分化和形态发生所需的细胞和分子相互作用现在是一个可以实现的目标。
