The Study of Palatal Cell Proliferation and Apoptosis in Retinoic Acid Induced Mouse Cleft Palate Varied with Different Developmental Stage

To determine the mechanisms and patterns of cleft palate induced by varied retinoic acid (RA) in different developmental stages of secondary palate, we detected the cell proliferation and apoptosis of palatal shelves by BrdU and TUNEL labeling on gestation day (GD) 10 and GD12 which RA was exposed, respectively. In GD10 RA treated group, the percentage of BrdU positive cells of embryonic palatal mesenchyme were lower than control group, while TUNEL expression was higher than control group. No significant difference was detected in GD12 RA treated group and in control group either in embryonic palatal mesenchyme or medial edge epithelium by BrdU and TUNEL labeling. Our data indicated that the mechanisms of RA induced cleft palate in the early developmental stage were the inhibition of proliferation of palatal mesenchymal cells and medial edge epithelium cells, as well as excessive induction of apoptosis.