Cellular and molecular mechanisms in the development of a cleft lip and/or cleft palate; insights from zebrafish (Danio rerio).

Human cleft lip and/or palate (CLP) are immediately recognizable congenital abnormalities of the face. Lip and palate develop from facial primordia through the coordinated activities of ectodermal epithelium and neural crest cells (NCCs) derived from ectomesenchyme tissue. Subtle changes in the regulatory mechanisms of NCC or ectodermal epithelial cells can result in CLP. Genetic and environmental contributions or a combination of both play a significant role in the progression of CLP. Model organisms provide us with a wealth of information in understanding the pathophysiology and genetic etiology of this complex disease. Small teleost, zebrafish (Danio rerio) is one of the popular model in craniofacial developmental biology. The short generation time and large number of optically transparent, easily manipulated embryos increase the value of zebrafish to identify novel candidate genes and gene regulatory networks underlying craniofacial development. In addition, it is widely used to identify the mechanisms of environmental teratogens and in therapeutic drug screening. Here, we discuss the value of zebrafish as a model to understand epithelial and NCC induced ectomesenchymal cell activities during early palate morphogenesis and robustness of the zebrafish in modern research on identifying the genetic and environmental etiological factors of CLP.