Reduplicated Basal Lamina of Small Venules and Mesothelium of Human Parietal Peritoneum: Ultrastructural Changes of Reduplicated Peritoneal Basement Membrane

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Abstract
We examined under the electron microscope samples of parietal peritoneum obtained from nine nondiabetic chronic uremics -six of them on maintenance intermittent peritoneal dialysis, ranging in age from 52 to 82 years -mean 64.4 ± 8.1 years and of nine non-uremic, non-diabetic patients -mean age 40.7 ± 12.2 years. Postcapillary venules and small venules showed areas with several layers of reduplicated basal lamina. Some microvessels showed gaps in basallamina with and/or without focal reduplication. Reduplicated submesothelial basal lamina was found in only one patient. These changes were not observed in the nine non-uremic, non-diabetic controls. To the best of our knowledge, this is the first description in humans of such alterations in the aforementioned locations, which may well be secondary to aging and/or to the intense mesothelial renewal observed in I.P.D. patients. We need to determine the possible influence of these ultrastructural changes on transperitoneal transfer of water and solutes during peritoneal dialysis. The basal lamina of blood vessels may not be of uniform thickness. Human non-diabetic adults show significant increase in capillary basal lamina thickness as one moves from head to foot (1). Those regional variations may be related to differences in venous hydrostatic pressure effective on the capillary bed (1). This paper decribes the first observations of reduplicated basal lamina of microvessels in the parietal peritoneum and of that subjacent to mesothelial cells in elderly, non-diabetic uremic patients.