Couly G F, Coltey P M, Le Douarin N M
Institut d'Embryologie cellulaire et moléculaire du CNRS et du Collège de France, Nogent-sur-Marne.
Development. 1993 Feb;117(2):409-29. doi: 10.1242/dev.117.2.409.
We have used the quail-chick chimera technique to study the origin of the bones of the skull in the avian embryo. Although the contribution of the neural crest to the facial and visceral skeleton had been established previously, the origin of the vault of the skull (i.e. frontal and parietal bones) remained uncertain. Moreover formation of the occipito-otic region from either the somitic or the cephalic paraxial mesoderm had not been experimentally investigated. The data obtained in the present and previous works now allow us to assign a precise embryonic origin from either the mesectoderm, the paraxial cephalic mesoderm or the five first somites, to all the bones forming the avian skull. We distinguish a skull located in front of the extreme tip of the notochord which reaches the sella turcica and a skull located caudally to this boundary. The former ('prechordal skull') is derived entirely from the neural crest, the latter from the mesoderm (cephalic or somitic) in its ventromedial part ('chordal skull') and from the crest for the parietal bone and for part of the otic region. An important point enlighten in this work concerns the double origin of the corpus of the sphenoid in which basipresphenoid is of neural crest origin and the basipostsphenoid is formed by the cephalic mesoderm. Formation of the occipito-otic region of the skeleton is particularly complex and involves the cooperation of the five first somites and the paraxial mesoderm at the hind-brain level. The morphogenetic movements leading to the initial puzzle assembly could be visualized in a reproducible way by means of small grafts of quail mesodermal areas into chick embryos. The data reported here are discussed in the evolutionary context of the 'New Head' hypothesis of Gans and Northcutt (1983, Science, 220, 268-274).
我们运用鹌鹑 - 鸡嵌合体技术研究了鸟类胚胎头骨骨骼的起源。尽管先前已确定神经嵴对面部和内脏骨骼的贡献，但颅顶（即额骨和顶骨）的起源仍不明确。此外，枕耳区域是由体节中胚层还是头部近轴中胚层形成，尚未进行实验研究。目前及先前研究获得的数据，使我们能够明确构成鸟类头骨的所有骨骼精确的胚胎起源，它们分别源自中外胚层、头部近轴中胚层或前五个体节。我们区分出位于脊索最前端到达蝶鞍前方的头骨，以及位于该边界后方的头骨。前者（“脊索前头骨”）完全源自神经嵴，后者腹内侧部分（“脊索后头骨”）源自中胚层（头部或体节），顶骨和部分耳区域源自神经嵴。这项研究揭示的一个重要点是蝶骨体的双重起源，其中基前蝶骨源自神经嵴，基后蝶骨由头部中胚层形成。骨骼枕耳区域的形成特别复杂，涉及前五个体节与后脑水平的近轴中胚层的协同作用。通过将鹌鹑中胚层区域小块移植到鸡胚中，能够以可重复的方式观察到导致最初拼图组装的形态发生运动。本文报道的数据将在甘斯和诺思卡特（1983年，《科学》，220卷，268 - 274页）“新头部”假说的进化背景下进行讨论。
