noun, plural: pseudostratified columnar epithelia
A special type of columnar epithelium composed of a single layer of columnar epithelial cells, which because of positioning and nuclei disposed at different levels appear to be stratified
A simple epithelium is an epithelial tissue that is composed of a single layer of epithelial cells. These cells are in direct contact with the basement membrane. This tissue may be classified histologically according to the shape of the cells it is made up of. It may be squamous (scale-like), cuboidal (cube-like), or columnar (column-like). In particular, a simple columnar epithelium is a columnar epithelial cells in a single layer. The cells are characteristically taller than wide. The nucleus in each cell is elongated and typically located near the base. These cells may be ciliated or non-ciliated. The presence of cilia aid in the movement of substances such as mucus across the surface. A special type of single columnar epithelium is the so-called pseudostratified. Its name is derived from its appearance. It seems it is a stratified type of epithelium but in truth is it is comprised of only one layer of cells. However, the cells are positioned in a way that there seems to be more than one layer. The nuclei are also disposed at different levels, resulting in a false stratification.
The pseudostratified columnar epithelia line the trachea and parts of the upper respiratory tract. The ciliated type is also referred to as respiratory epithelium.
- pseudostratified columnar epithelial tissue