serous membrane (serosa) A tissue consisting of a layer of mesothelium attached to a surface by a thin layer of connective tissue. Serous membrane lines body cavities that do not open to the exterior; the peritoneum, pleura, and serous pericardium are examples.

serous membrane (serosa) n. a smooth transparent membrane lining certain large cavities of the body, such as the abdomen (see peritoneum) and chest (see pleura). The parietal portion of the membrane lines the walls of the cavity, and the visceral portion covers the organs concerned. The two form a closed sac, the inner surface of which is moistened by a thin fluid derived from blood serum, allowing frictionless movement of organs within their cavities. Compare mucous membrane.

serous membrane In vertebrates, the type of membrane that lines the surface of coelomic cavities (i.e. body cavities that are not open to the exterior). It is composed of a single layer of plate-like cells (mesothelium) attached to the surface by a layer of connective tissue.