Fine structure of the frog palate mucociliary epithelium.

The mucociliary epithelium (MCE) of the frog palate is a pseudostratified columnar respiratory epithelium supported by connective tissue with no submucosal glands. Morphologically different types of cells have been identified using scanning and transmission electron microscopy: ciliated cells, mucous and serous cells, intermediate cells, basal cells, and patches of vomero-nasal epithelium with sensory receptors and supporting cells. The cilia of the MCE of the frog palate are 5 to 7 microns long and a cluster of 3 to 7 projections forms a ciliary crown at their tips. Using cationized ferritin, anionic charges are identified on their whole outer surface. The mucus discharged by the secretory cells forms a continuous blanket which lies at the tips of the cilia.