Cleft palate is a common craniofacial anomaly requiring complex multidisciplinary treatment and having lifelong implications for affected individuals. The etiology of cleft palate is multifactorial, with both genetic and environmental factors playing a role. A cleft palate arises when during embryonic development the nasal and oral cavities fail to separate. Commonly, this occurs when the palatal shelves that form the secondary palate fail to develop properly. The palatal shelves arise from the first branchial arch as two lobes of neural crest-derived mesenchyme covered by ectodermal-derived epithelium. During development they rapidly grow and change from a vertical to a horizontal position allowing their tips to approach and contact each other. Upon contact, the epithelial cells adhere and intercalate to form the midline epithelial seam. These epithelial cells subsequently disappear by apoptosis, epithelial to mesenchymal transformation, and migration, leaving a confluent, scarless mesenchyme at the midline behind.
If any of these processes is disrupted or if their timing is disturbed, a cleft palate may result. Progress in recent years led to the identification of many genes that when inappropriately expressed, defective, or absent will result in cleft palate in humans or mice. Amongst them are numerous transcription factors (e.g. Tbx1, Tbx22, Msx1, IRF6) and signaling molecules and their receptors (e.g. Tgfß3, Tgfßr2, Fgf8, Fgfr1, Fgfr2, Bmp7). However, it is clear that environmental factors are also important. How these environmental factors interact with cellular and molecular events during early development of the embryo is only one of the questions that remain about the intricate developmental processes during palate development.
This special topic will present a series of original research papers, clinical cases, concise reviews, and opinions with aim to advance our conceptual understanding of this very fascinating part of craniofacial development.
Cleft palate is a common craniofacial anomaly requiring complex multidisciplinary treatment and having lifelong implications for affected individuals. The etiology of cleft palate is multifactorial, with both genetic and environmental factors playing a role. A cleft palate arises when during embryonic development the nasal and oral cavities fail to separate. Commonly, this occurs when the palatal shelves that form the secondary palate fail to develop properly. The palatal shelves arise from the first branchial arch as two lobes of neural crest-derived mesenchyme covered by ectodermal-derived epithelium. During development they rapidly grow and change from a vertical to a horizontal position allowing their tips to approach and contact each other. Upon contact, the epithelial cells adhere and intercalate to form the midline epithelial seam. These epithelial cells subsequently disappear by apoptosis, epithelial to mesenchymal transformation, and migration, leaving a confluent, scarless mesenchyme at the midline behind.
If any of these processes is disrupted or if their timing is disturbed, a cleft palate may result. Progress in recent years led to the identification of many genes that when inappropriately expressed, defective, or absent will result in cleft palate in humans or mice. Amongst them are numerous transcription factors (e.g. Tbx1, Tbx22, Msx1, IRF6) and signaling molecules and their receptors (e.g. Tgfß3, Tgfßr2, Fgf8, Fgfr1, Fgfr2, Bmp7). However, it is clear that environmental factors are also important. How these environmental factors interact with cellular and molecular events during early development of the embryo is only one of the questions that remain about the intricate developmental processes during palate development.
This special topic will present a series of original research papers, clinical cases, concise reviews, and opinions with aim to advance our conceptual understanding of this very fascinating part of craniofacial development.
