ABSTRACT
The pleural cavity is a space between the visceral pleura, which covers the entire surface of the lung including the lobar septum, and the parietal pleura, which covers the inner surface of the thoracic cage, mediastinum, and diaphragm. The thickness and structure of the visceral pleura vary substantially between various species of animals. Pleurolymphatic communication has been found only on some portions of the parietal pleura but not on the visceral pleura. The pleural cavity is better known for its disorders than for its normal functions because it is vulnerable to and readily shows alterations in many cardiopulmonary and other diseases. The easiest way to introduce tracer materials into the pleural cavity is through the intercostal space. Intravenous or subcutaneous introduction of foreign particles can be done readily in larger animals. Fluids and particulate matter injected into the pleural cavity can be detected by gross and light microscopic examination to accumulate in the mediastinal lymphatic channels and nodes.
