Johnston M C, Millicovsky G
Clin Plast Surg. 1985 Oct;12(4):521-32.
Largely because fusion of the lip and the palate are developmental weak points, common facial clefts may arise in a great many ways, both experimentally and in man. However, we believe that the vast majority of human clefts have similar origins with minor variations. One must always question the appropriateness of animal models. Apparently appropriate animal models are giving us considerable insight into the manner in which genetic and environmental factors alter development and how they interact with one another in the developing embryo. These studies help us understand the nature of the multifactorial threshold concept as it applies to cleft lip and cleft palate, and they emphasize the potential importance of even "minor" environmental factors in determining on which side of the threshold for clefting an individual embryo may fall.
很大程度上由于唇和腭的融合是发育薄弱点，无论是在实验中还是在人类身上，常见的面部裂隙可能以多种方式出现。然而，我们认为绝大多数人类裂隙起源相似，只是存在微小差异。人们必须始终质疑动物模型的适用性。显然合适的动物模型正在让我们深入了解遗传和环境因素改变发育的方式，以及它们在发育中的胚胎中如何相互作用。这些研究有助于我们理解多因素阈值概念在唇腭裂中的应用本质，并且它们强调了即使是“微小”环境因素在决定单个胚胎可能落在腭裂阈值的哪一侧方面的潜在重要性。
