The peritoneum is the largest and the most complex arranged serous membrane in the body that lines both the intra-abdominal wall and the viscera contained within the peritoneal cavity. It is capable of walling off infections and has several functions such as the ability to synthesise, secrete or absorb. The peritoneum diminishes friction among abdominal viscera, thereby enabling their free movement. With a surface area of some 10,000 cm2 in adults , almost equal to that of the skin, this membrane may be considered among the largest organs in humans. The peritoneal cavity normally contains less than 100 ml of serous fluid that resembles an ultrafiltrate of plasma and contains less than 3 g/dl protein. Taken together the surface area and the functional capacity of the peritoneum, this enables the peritoneal cavity to be used for continuous ambulatory dialysis (CAPO) as well as an internal reservoir during drainage procedures (i.e. ventriculoperitoneal shunts). The peritoneum and the serosal surfaces of organs within the peritoneal cavity are composed of mesothelium and sub-mesothelial connective tissue. Highly differentiated mesothelial cells, resting on a basement membrane, overly the connective tissue. Embedded in this layer are numerous blood vessels and lymphatics. In terms of blood supply per mass, the peritoneum is one of the most richly vascularised organs. Interspersed among the connective tissue are poorly differentiated, epithelioid-like cells similar to fibroblasts (figure 1.1 ). Injury of the peritoneum triggers a series of events aimed at mesothelial regeneration. Some of the prinCipal elements in the regenerative process are leukocyte influx into the abdominal cavity, fibrin deposition and activation of both peritoneal macrophages and the normally quiescent mesothelial cells.

University Hospital Rotterdam Dijkzigt, Stichting Erasmus Heelkundig Kankeronderzoek
J. Jeekel (Hans)
Erasmus University Rotterdam
Erasmus MC: University Medical Center Rotterdam