DEVELOPMENT OF HEAD NERVES, BLOOD VESSELS, BONES, MUSCLE

了解颅面发育需要许多胚胎 定义流程。其中包括所有面部的胚胎起源 组织，包括肌肉、软骨和骨骼。此外, 必须分析头面部组织的发育模式。 图案化包括每个结构在 正确的位置和合适的初始形状。最近我 发现鸟类胚胎中的头部随意肌肉是由 来自轴旁中胚层，而不是如所有 胚胎学短信。这些数据否定了臂肌的概念， 这是许多头部发育模型的一个关键方面。中的肌肉 头部的不同部分只是在它们的起源方面有所不同 结缔组织成分。神经脊细胞向鳃中迁移 原基，随后从细胞学上转化为 同质种群转化为一系列骨架元素，每个骨架元素都有一个 形状对于它在拱门内的位置是唯一的，也适合于 特别的拱门。在假定的第一拱(较低的)被替换之后 第二弓(舌骨)原基的神经脊细胞， 小鸡胚胎发育有两套完整的下巴组织， 第二个牙弓位置的正常颌骨和异位颌骨。这些 数据表明，一些头面部骨骼的花纹基础 结构是神经冠种群在发病前所固有的 迁移。在这些胚胎中，许多自愿的肌肉也是 重新排列，这表明肌肉依赖于图案 位于结缔组织原基内的信息。这个 本研究的目的是完成正常肌肉的标测 起源于禽类胚胎，并从实验上分析其机制 头面部的结缔组织，肌肉，还有运动神经 血管通常是有图案的。这些过程是 理解这两种常态的基础的根本重要性 发育和颅面畸形。

Understanding craniofacial development requires that many embryonic processes be defined. Among these are the embryonic origins of all facial tissues, including muscles, cartilages and bones. In addition, developmental patterning of craniofacial tissues must be analyzed. Patterning includes the mechanisms by which each structure forms in the correct location and with the appropriate initial shape. Recently I discovered that cephalic voluntary muscles in avian embryos are derived from paraxial mesoderm, not from branchial mesoderm as is stated in all embryology texts. These data negate the concept of branchiomeric muscles, which is a key aspect of many models of head development. Muscles in different parts of the head differ only with respect to the origin of their connective tissue components. Neural crest cells migrate into branchial arch primordia and are subsequently transformed from cytologically homogeneous populations into a series of skeletal elements, each having a shape unique to its position within the arch and also appropriate for the particular arch. Following substitution of presumptive first arch (lower jaw) neural crest cells for presumptive second arch (hyoid) primordia, chick embryos developed with two complete sets of lower jaw tissues, the normal jaw and an ectopic jaw in the location of the second arch. These data indicate that the basis for patterning of some craniofacial skeletal structures is inherent in the nural crest population before the onset of migration. In these embryos many of the voluntary muscles were also rearranged, suggesting that muscles are dependent upon patterning information residing within the connective tissue primordia. The objectives of this research are to complete the mapping of normal muscle origins in the avian embryo, and to experimentally analyze the mechanisms by which craniofacial connective tissues, muscles, and also motor nerves and blood vessels are normally patterned. These processes are of fundamental importance in understanding the basis for both normal development and craniofacial dysmorphologies.