Anatomy of the Peritoneal Membrane

Abstract

The increasing use of peritoneal dialysis in the treatment of end-stage renal disease has stimulated interest in the structure of the peritoneal membrane and the mechanism(s) by which water and various solutes cross this membrane during peritoneal dialysis . Despite extensive anatomical and physiological studies of the microvasculature and a better understanding of the movement of various solutes across the capillaries many controversies surround peritoneal transport and many questions remain unanswered (1). Furthermore we know little about the contribution to solute transport of the peritoneal lymphatics which are found in the diaphragmatic peritoneum and also in the avascular areas of mesentery. The lymphatics, especially those of the diaphragmatic peritoneum appear to be important in the absorption of solutes, and are the principal route of drainage of fluid from the peritoneal cavity (2-10) .In contrast, strong indirect evidence ( 11 ) suggests that the major route of solute removal during peritoneal dialysis is through the peritoneal capillaries . Today it is widely accepted that the peritoneal membrane consists of three layers: a) the capillary endothelium -with its basement membrane and pericytes; b) the peritoneal interstitium and c) the mesothelium with its basement membrane (Fig. 1). This paper will discuss these three components of the peritoneal membrane and their contribution to the fluid and solute exchange between blood and fluid in the peritoneal cavity.