Epithelial alterations of secondary palate formation.

This study was undertaken to examine the normal and abnormal epithelial alterations of secondary palate in rats. Control and dexamethasone-treated embryos and fetuses of Wistar rats were evaluated by macroscopic and scanning electron microscopic analysis prior to, during, and after fusion of palatal processes. Normal alterations of the surface topography included growth and disorganization of medial edge epithelial cells followed by fusion and posterior migration to both the oral and nasal aspects of the palate. No evidence of epithelial cell death or transformation was observed. Dexamethasone-treated fetuses showed epithelial cells increased in size with a large amount of desquamation, followed by deposition of a disorganized cell layer with keratin-like characteristics. This allowed no fusion of palatal processes.