by Katherina Baranova MD and Matt Cecchini MD FRCPC
May 26, 2022
The surface of your lungs and chest wall are covered by a thin type of tissue called pleura. The pleura that covers the lung is called the visceral pleura and the pleura that covers the chest wall is known as the parietal pleura. The two layers of pleurae can be understood as a balloon within a balloon. The inner visceral pleura and outer parietal pleura are separated by a thin space called the pleural cavity or pleural space.
Pathologists call the pleural cavity a potential space because it is not usually filled with air. In normal conditions, there is a thin layer of fluid between the two layers of pleura. Under the microscope, the pleura is made up of a layer of cells called mesothelial cells. These cells are small, flat to cuboidal cells, with well-defined cell borders. The part of the cell that holds the genetic material of the cell, the nucleus, is usually found in the center of the cell.