Fenestrated capillaries in human parietal and rabbit diaphragmatic peritoneum

Samples of parietal peritoneum from 20 patients (11 of them chronic uremics) and biopsies of diaphragmatic peritoneum from 5 apparently normal female New Zealand rabbits were examined by electron microscopy. One out of 20 patients and 3 out of 5 rabbits showed fenestrated capillaries. This report is the first published demonstration of the existence of fenestrated capillaries in human parietal and rabbit diaphragmatic peritoneum. They represented a small fraction of the peritoneal microvascular bed which was mainly formed by capillaries of the continuous type. Fenestrae of the observed fenestrated capillaries showed diaphragms. Results of this study indicate that different peritoneal microvascular segments can show different microvascular ultrastructures and possibly have a different physiology and different mechanisms of transperitoneal transfer of water and solutes.