Pseudostratified epithelium is a normal part of the human body.
pseudostratified columnar epithelium
The cells that line the epithelium in the tracheae are ciliated pseudostratified columnar epithelium cells.They are of three types -ciliated cellsgoblet cellsbasal cells
psuedostratified ciliated columnar epithelial cells and goblet cells
pseudostratified ciliated columnar epithelium
Pseudostratified columnar epithelium is an epithelial tissue comprised of only one layer of cells. The nuclei of these column shaped cells are located at varying levels which make it appear as though there are multiple layers.
Plant and animal cell
trachea
pseudostratified columnar epithelium
Cilia
Pseudostratified columnar epithelium
This is called metaplasia.
The tracheal epithelium is thick and has the appearance of more than 1 layer of cells. The tracheal epithelium gives an optical illusion of being pseudostratified due to the nuclei of cells on different levels, thus making it look multi layered.