Growth inhibition and occurrence of cleft palates due to hypervitaminosis A

Summary DNA synthesis in palatal processes obtained from fetal rats was 36% lower in the presence of excess vitamin A, but vitamin A-exposed maxillary explants showed only a modest decrease. Scanning electron micrographs of fetuses exposed to hypervitaminosis A in utero demonstrated both decreased head size and stunted palatal processes. The results suggest that cleft palates occur in this model system because the palatal processes are more sensitive to the actions of vitamin A than are the surrounding maxillary tissues.Acknowledgments. We thank Dr Samuel M. Meller, Assistant Professor of Anatomy, Harvard Medical School, for his assistance in obtaining the scanning electron micrographs. This project was supported in part by grant DE-04684 from the National Institute of Dental Research.