Ultrastructural morphology of the normal nasal respiratory epithelium of the mouse.

Abstract

AbstractThe nasal respiratory epithelium of the mouse has been studied at the ultrastructural level. The tissue was found to be a rather typical pseudostratified columnar ciliated epithelium, superficially different but basically similar to tracheal and bronchial epithelium in the same species, and clearly similar in most respects to that of other mammals. Four cell types were distinguished: ciliated columnar, secretory (goblet), intermediate, and basal.The ciliated cells, which exhibited typical surface cilia and microvilli, were characterized by a distinct stratification in the arrangement of subcellular components in their supranuclear cytoplasm. Beginning at the apical end and proceeding basally, the following strata were seen: an ectoplasmic region relatively free of organelles; an area rich in vesicular and tubular membrane profiles; a mitochondrial zone; a layer rich in ribosomes and polyribosomes; and a stratum of Golgi complexes.Secretory (goblet) cells were observed at various stages of secretion droplet accumulation. Cells in the earliest stage, characterized by a dense content of sER in the supranuclear cytoplasm, were similar to the “non‐ciliated” cells of the mouse's lower respiratory tract. Some of the secretory cells contained dilated cisternae of rER which were engorged with a relatively electron‐dense material. The possible significance of these inclusions is discussed.Unlike the other cell types, intermediate and basal cells displayed no features indicative of specialized function.