
Mesothelial membranes are made up of two different layers, called the parietal and visceral layers. Parietal layers are outer layers, and these typically cover large areas such as the chest cavity (in the case of pleural and pericardial membranes) and the abdominal cavity (as in the case of peritoneal membranes). Visceral layers are those that cover organs such as the lungs and heart.