The developing ferret palate--a scanning electron microscope study: I. Primary palate and secondary palatal shelves.

Palatogenesis was studied in the ferret (Mustela putorius) from day 27 to day 29 of gestation. At day 27 the primary palate is present as a flattened shield area, and the two secondary palatal shelves are directed at 45 degrees to the horizontal plane, passing downward on the lateral sides of the tongue, which occupies the space between them. By day 28 the primary palate is bulging convexly in the oral cavity, and the secondary palatal shelves have elevated and are in contact in the midline. Finally, at day 29 the primary palate and nasal septum are in contact with the two secondary palatal shelves. During fusion of the secondary palatal shelves, no structures (leading edges or filopedia) associated with cell movement were apparent. It is suggested there are two stages of secondary palate formation in the ferret; an initial contacting of the secondary palatal shelves with the production of cell debris, and further midline movement of the shelves and cell migration out of the epithelial seam.