pleura /plo͝or″ə/ pl. pleurae [Gk, rib] , a delicate serous membrane enclosing the lung, composed of a single layer of flattened mesothelial cells resting on a delicate membrane of connective tissue. Beneath the membrane is a stroma of collagenous tissue containing yellow elastic fibers. The pleura divides into the visceral pleura, which covers the lung, dipping into the fissures between the lobes, and the parietal pleura, which lines the chest wall, covers the diaphragm, and reflects over the structures in the mediastinum. The parietal and visceral pleurae are separated from each other by a small amount of fluid that acts as a lubricant as the lungs expand and contract during respiration. See also pleural cavity, pleural space. −pleural, adj.
