Collagenous membrane from the surface of human visceral pleura

A pleural surface membrane, which could be ablated from frozen human lungs with forceps, has been analyzed chemically. The surface membrane was found to consist primarily of collagen (Type I) and to contain only 2.3–8% elastin. The mechanical properties of this membrane should differ markedly from those of alveolar parenchyma, since the connective tissue of the parenchyma contains 32% elastin.