Mechanism of hematuria. I. Electron microscopic demonstration of the passage of a red blood cell through a glomerular capillary wall in rat masugi nephritis.

Masugi nephritis was induced in Sprague-Dawley rats by an intravenous injection of rabbit anti-rat kidney serum. In the autologous phase of the disease, three of 18 rats manifested continuous hematuria. Ultrastructural examination of renal glomeruli by transmission and scanning microscopy revealed gaps in the basement membranes, and the transcapillary passage of red blood cells through the discontinuous regions in the hematuric rats. Control animals revealed no gaps in the glomerular basement membranes regardless of the method used in their preparation for electron microscopy. These data support the hypothesis that hematuria is a result of the passage of red blood cells through gaps in the glomerular basement membrane in Masugi nephritis.