Diewert V M, Wang K Y
Department of Clinical Dental Sciences, University of British Columbia, Vancouver.
Crit Rev Oral Biol Med. 1992;4(1):111-30. doi: 10.1177/10454411920040010201.
During the sixth week of human development, the primary palate develops as facial prominences enlarge around the nasal pits to form the premaxillary region. Growth of craniofacial components changes facial morphology and affects the extent of contact between the facial prominences. Our recent studies have focused on developing methods to analyze growth of the primary palate and the craniofacial complex to define morphological phases of normal development and to determine alterations leading to cleft lip malformation. Analysis of human embryos in the Carnegie Embryology Collection and mouse embryos of cleft lip and noncleft strains showed that human and mouse embryos have similar phases of primary palate development: first, an epithelial seam, the nasal fin, forms; then a mesenchymal bridge develops through the nasal fin and enlarges rapidly. A robust mesenchymal bridge must form between the facial prominences before advancing midfacial growth patterns tend to separate the facial components as the medial nasal region narrows and elongates, the nasal pits narrow, and the primary choanae (posterior nares) open posterior to the primary palate. In mouse strains with cleft lip gene, maxillary growth, nasal fin formation, and mesenchymal replacement of the nasal fin were all delayed compared with noncleft strains of mice. Successful primary palate formation involves a sequence of local cellular events that are closely timed with spatial changes associated with craniofacial growth that must occur within a critical developmental period.
在人类发育的第六周，随着鼻窝周围的面部隆起扩大，形成上颌前部区域，原腭开始发育。颅面组成部分的生长改变面部形态，并影响面部隆起之间的接触范围。我们最近的研究集中在开发分析原腭和颅面复合体生长的方法，以确定正常发育的形态阶段，并确定导致唇裂畸形的改变。对卡内基胚胎学收藏中的人类胚胎以及唇裂和非唇裂品系的小鼠胚胎进行分析后发现，人类和小鼠胚胎的原腭发育阶段相似：首先，形成一个上皮缝，即鼻鳍；然后，一个间充质桥通过鼻鳍发育并迅速扩大。在中面部生长模式向前推进之前，面部隆起之间必须形成一个强大的间充质桥，因为随着内侧鼻区变窄和拉长、鼻窝变窄以及原腭后方的原发后鼻孔（后鼻孔）打开，中面部生长模式往往会使面部各部分分离。与非唇裂小鼠品系相比，在具有唇裂基因的小鼠品系中，上颌生长、鼻鳍形成以及鼻鳍的间充质替代均延迟。成功的原腭形成涉及一系列局部细胞事件，这些事件与颅面生长相关的空间变化密切同步，而颅面生长必须在关键的发育时期内发生。
