Cleft palate represents one of the highest frequencies of congenital malformations found in the human. Teratogens or mutant genes whic delay palate shelf movement could be responsible for the congenital defect. The principal objective of the proposed research is to gain an understanding of the processes by which teratogens affect morphogenetic pathways. This objective will be pursued by (1) biochemical, morphological, pharmacological and genetic analyses to elucidate the mechanism of palate shelf rotation, and (2) the determination of the mechanism by which glucocorticoids interfere with palate shelf development and cause cleft palate. Among the specific objectives are: (1) to determine actin and myosin in palate with time of development and their relative proportion in the anterior and posterior end; (2) to observe morphologically any contractile apparatus in the palate; (3) to test whether contractile proteins function in palate rotation, either in the shelves or outside; and (4) to determine whether glucocorticoids affect the putative contractile apparatus and might therefore cause cleft palate.