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.
This study reconstructs the whole sequence of mesothelial injury and regeneration in patients on longterm peritoneal dialysis. Our observations indicate that peritoneal dialysis induces a process of continuous mesothelial injury and regeneration. New mesothelial cells seem to originate from wandering mesothelial cells of the peritoneal fluid, as well as from mesothelial cell precursors localized in the sub-mesothelial connective tissue.
SUMMARY Patterns of pertechnetate uptake were correlated with ultrastructural properties of the endothelial wall in 14 human brain tumours. In tumours with reduced uptake of the radionuclide, intercellular tight junctions were observed whereas absence of intercellular tight junctions was characteristic of all tumours with an increased uptake of pertechnetate. In some tumours with increased uptake, fenestrated endothelial wall was seen while in others nonfenestrated wall was evident. We concluded that intercellular junctions and not fenestrations affect the permeability of brain tumours to pertechnetate. (Penning and Front, 1975). Two main factors govern the passage of Tc-pertechnetate from the blood into the tissue of the tumours-the vascularity of the tumour, and the permeability of the blood-brain barrier.In a previous study, uptake of pertechnetate was found to be independent of vascularity (Front, 1978). It was suggested that changes in the bloodbrain barrier, which is localised in the capillary wall, might be involved with the different rates of 99mTc-pertechnetate uptake. In the present study we extended our investigations to include the ultrastructural properties of the capillary wall. Thus, both scintigraphic assessments and electron microscopic studies were carried out on the same tumour, in order to correlate given ultrastructural features with scintigraphic patterns of pertechnetate uptake.
Subjects and methodsFourteen patients whose clinical condition enabled detailed scintigraphic assessments and whose removed tumours were adequately processed for
In this study, samples of mesenteric diaphragmatic peritoneum and peritoneum covering the inner side of the ventral abdominal wall of apparently normal rabbits were examined under electron microscopy. Mesentery appeared as the most vascularized peritoneal segment (71.1% of the total number of observed capillaries). Diaphragmatic and parietal peritoneum contributions to the total examined microvascular bed were of 17.9% and 10.9% respectively. Only 3.2% of peritoneal diaphragmatic capillaries were of the fenestrated type. This qualitative and quantitative heterogeneity of the peritoneal microcirculation combined with the different contribution of each peritoneal segment to the total peritoneal surface area, the different mesothelial cell density of visceral and parietal peritoneum, and the different permeability of parietal visceral peritoneum suggest that, in vivo, whole organ permeability studies would eventually show just an average of an unknown distribution of segmental peritoneal permeabilities.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.