Which tissue is characterized by a single layer of flat cells and is also known as pavement epithelium?

Which tissue is characterized by a single layer of flat cells and is also known as pavement epithelium?

• A. Simple cuboidal epithelium
• B. Stratified squamous epithelium
• C. Pseudostratified ciliated columnar epithelium
• D. Simple squamous epithelium

Answer: (D)

Identifying epithelial tissue by cell shape and layering is the idea here. Pavement epithelium is simple squamous epithelium—a single layer of flat, tile-like cells. This thin, smooth lining is ideal for diffusion and filtration, which is why you see it where rapid exchange occurs, such as in the walls of capillaries and the air sacs of the lungs, as well as lining body cavities (mesothelium) and kidney structures. The other options don’t fit because they describe different arrangements: a single layer of cube-shaped cells is simple cuboidal; multiple layers of flat cells are stratified squamous; and pseudostratified ciliated columnar epithelium looks multi-layered but each cell contacts the basement membrane and is typically columnar with cilia. Thus, the description matches simple squamous epithelium, the pavement epithelium.

Identifying epithelial tissue by cell shape and layering is the idea here. Pavement epithelium is simple squamous epithelium—a single layer of flat, tile-like cells. This thin, smooth lining is ideal for diffusion and filtration, which is why you see it where rapid exchange occurs, such as in the walls of capillaries and the air sacs of the lungs, as well as lining body cavities (mesothelium) and kidney structures.

The other options don’t fit because they describe different arrangements: a single layer of cube-shaped cells is simple cuboidal; multiple layers of flat cells are stratified squamous; and pseudostratified ciliated columnar epithelium looks multi-layered but each cell contacts the basement membrane and is typically columnar with cilia. Thus, the description matches simple squamous epithelium, the pavement epithelium.