During craniofacial development, defective growth and fusion of the upper lip and/or palate can cause orofacial clefts (OFCs), which are among the most common structural birth defects in humans. The developmental basis of OFCs includes morphogenesis of the upper lip, primary palate, secondary palate, and other orofacial structures, each consisting of diverse cell types originating from all three germ layers: the ectoderm, mesoderm, and endoderm. Cranial neural crest cells and orofacial epithelial cells are two major cell types that interact with various cell lineages and play key roles in orofacial development. The cellular basis of OFCs involves defective execution in any one or several of the following processes: neural crest induction, epithelial‐mesenchymal transition, migration, proliferation, differentiation, apoptosis, primary cilia formation and its signaling transduction, epithelial seam formation and disappearance, periderm formation and peeling, convergence and extrusion of palatal epithelial seam cells, cell adhesion, cytoskeleton dynamics, and extracellular matrix function. The latest cellular and developmental findings may provide a basis for better understanding of the underlying genetic, epigenetic, environmental, and molecular mechanisms of OFCs.

中文翻译：

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口面部裂隙的细胞和发育基础。

在颅面发育过程中，上唇和/或上颚的发育缺陷和融合会导致口面部裂隙 (OFC)，这是人类最常见的结构性先天缺陷之一。OFC 的发育基础包括上唇、初级上颚、次级上颚和其他口面部结构的形态发生，每个结构都由源自所有三个胚层的不同细胞类型组成：外胚层、中胚层和内胚层。颅神经嵴细胞和口面部上皮细胞是与各种细胞谱系相互作用并在口面部发育中起关键作用的两种主要细胞类型。OFC 的细胞基础涉及以下任一或几个过程的缺陷执行：神经嵴诱导、上皮间质转化、迁移、增殖、分化、凋亡、初级纤毛形成及其信号转导、上皮接缝的形成和消失、周皮的形成和脱皮、腭上皮接缝细胞的汇聚和挤压、细胞粘附、细胞骨架动力学和细胞外基质功能。最新的细胞和发育发现可能为更好地了解 OFC 的潜在遗传、表观遗传、环境和分子机制提供基础。