Mesothelial injury and recovery.

This paper describes the cytologic effects of drying or wetting of visceral peritoneum and the course of mesothelial regeneration. Using en face silver staining and electron microscopy, it was found that mesothelial cells disappeared from the surface after the cecum was either briefly dried or kept wet with isotonic saline for 30 minutes; the fibrin-slide technic showed that such injury caused a loss of the normal serosal fibrinolytic activity. In following the course of mesothelial regeneration using the same technics, it was apparent that free-floating peritoneal mononuclear cells settled on the denuded surface where they spread out, attached to one another, and developed features (eg, microvilli) typical of mature mesothelial cells; such new mesothelium showed a greatly enhanced fibrinolytic activity.

Postoperative peritoneal adhesions. A study of the mechanisms.

THIS PAPER DESCRIBES AN EXPERIMENTAL MODEL OF PERITONEAL ADHESIONS, IN THE RAT, BASED ON TWO RELATIVELY MINOR ACCIDENTS THAT MAY OCCUR DURING ABDOMINAL SURGERY IN MAN: drying of the serosa, and bleeding. Drying alone had little effect; drying plus bleeding consistently produced adhesions to the dried area. Fresh blood alone produced adhesions between the three membranous structures [omentum and pelvic fat bodies (PFBs)]. The formation of persistent adhesions required whole blood. Preformed clots above a critical size induced adhesions even without previous serosal injury; they were usually captured by the omentum and PFBs. If all three membranous structures were excised, the clots caused visceral adhesions. The protective role of the omentum, its structure, and the mechanism of omental adhesions, are discussed. These findings are relevant to the pathogenesis of post-operative adhesions in man.