The Pleura: General Aspects

Abstract

The pleura comprises the visceral and the parietal pleura, and this forms two layers which merge into each other in the hilum of the lung. The reflective surfaces of the healthy pleura (Fig. 16.1) are separated from each other by the capillary space filled with approximately 3 ml of pleural fluid. The visceral pleura is attached directly to the lung and is about 100–200 μm thick. The superficial mesothelium (covering cell layer) is formed by the mesothelial cells which are joined with desmosomes and demonstrate microvilli on their surface. On the inside are three layers of connective tissue delineated by a basal membrane. The main connective tissue layer of the pleura is formed by an external and internal border lamina with a fibrous layer in between, which controls the blood vessels. The internal lamina borders on the alveolar wall and is connected to the interstitial connective tissue of the lung in the area of the lobular septum. The parietal pleura borders on the intercostal muscles and ribs over the endothoracic fascia.