Ultrastructural observations of chronic uremic lungs with special reference to histochemical and X-ray microanalytic studies on altered alveolocapillary basement membranes.

Electron microscopic observations of chronic uremic lungs were carried out in 6 uremic patients with special reference to histochemical and X-ray microanalytic studies on the altered alveolocapillary basement membranes. Epithelial damage varying from edematous swelling of the epithelial cells to total disruption and desquamation of the epithelium was often present. Although degenerative changes of capillary endothelium such as swelling and vacuolization of the endothelial cells were not infrequently demonstrated, total destruction of the endothelium was rarely seen. The interstitial changes included focal accumulation of edema fluid, particularly in the pericapillary spaces, patchy fibrosis, and increased cellularity. Particularly interesting were the altered alveolocapillary basement membranes which showed irregular thickening, lamination, and fragmentation. Irregular electron densities with derangement of internal ultrastructures were often observed in the matrices of isolated uremic lung basement membranes. The anionic binding sites characterized by cationized ferritins appeared to be irregularly and loosely arranged on the surfaces and in the interior of isolated basement membranes. In addition, abnormal deposition of aluminum was consistently detected in the precipitates of isolated basement membranes. From the aforementioned results we conclude that the present investigation provides the morphological data at the ultrastructural and molecular level to explain many of pulmonary physiological alterations and clinical manifestations exhibited by patients with chronic uremia.