Mesothelial hyperplasia in response to peritoneal dialysis fluid: a morphometric study in the rat

Five rats were given twice daily intraperitoneal injections of hypertonic dialysis fluid for 6 weeks. The structure of the hepatic peritoneum of this group was compared with that of a control group by applying morphometric techniques to transmission electron micrographs. The experimental group showed marked mesothelial hyperplasia with doubling of the number of cells and a significant increase in the length of intercellular junction per unit area of peritoneum. Since cell volumes in the two groups were similar, the increase in cell density in the experimental animals was the result of the cells assuming a more cuboidal shape. Experimental animals also showed an increase in the number of microvilli, pinocytotic vesicles and rough endoplasmic reticulum per unit area of peritoneum. Chronic exposure to dialysis fluid has profound effects on the number, shape and composition of peritoneal mesothelial cells in the rat.