The Journal of craniofacial surgery
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Although the mechanism by which retinoic acid (RA) induces cleft palate has been intensely investigated, some controversies remain. Some researchers argue that RA inhibits apoptosis, resulting in a failure of palatal shelves to fuse, whereas others propose that RA disrupts elevation or retards the growth of palatal shelves. This study investigated the mechanism underlying RA-induced formation of cleft palate in the rat, focusing mainly on the role of apoptosis. ⋯ Apoptotic manifestations did not differ between RA-induced cleft palates and control palates, suggesting that apoptosis makes a minimal contribution to the cleft palate formed in response to RA. Instead, growth retardation of the palatal shelves appears to play a major role in RA-induced cleft palate.