The morphology of parietal peritoneum: a scanning electron micrograph study.

From 1988 to 1992, 114 patients with end-stage renal failure were treated with continuous ambulatory peritoneal dialysis (CAPD). In 30 patients (18 men, 12 women, age 31-80 years), 40 scanning electron micrographs (SEM) of parietal peritoneal tissue, obtained with biopsy, were performed: in 20 patients at the time of the first catheter implantation, in 14 patients after catheter removal (because of peritonitis in 12 patients and drainage problems in 2 patients), and in 6 patients during catheter reinsertion. In uremic patients two types of mesothelial cells were observed: hexagonal and elongated. In some patients microvilli were abundant and covered the whole surface of mesothelial cells; in other patients microvilli were lacking. Wide openings (stomata) between mesothelial cells were found in some cases, which were wider in patients with peritonitis. During peritonitis, microvilli disappeared, and mesothelial cells were covered with fibrin, leukocytes, and erythrocytes instead. In the majority of patients with peritonitis, mesothelial cells were totally peeled away, or removed, leaving a denuded surface of fibrous tissue. A recovery of the parietal peritoneum was observed in one patient at the time of peritoneal catheter reinsertion: a complete mesothelial regeneration with abundant microvilli appeared. In other patients the surface was denuded, without microvilli or mesothelial cells, covered with fibrin and fibrous tissue. Despite observed changes of the parietal peritoneum with SEM during the course of CAPD and peritonitis, changes may be reversible due to regeneration of mesothelial cells. Prolonged changes after discontinuation of peritoneal dialysis may persist in patients without mesothelial cell regeneration or with a defective process of fibrinolysis.