Early ultrastructural glomerular alterations in neonatal nephrotic mice (ICGN strain).

ICGN is a strain of mice with hereditary nephrotic syndrome of an unknown cause. In this study, early glomerular alterations in newborn ICGN mice were observed with electron microscopy to gain a better insight into the onset of the disease. Development of the glomeruli was normal until fusion of epithelial and endothelial basement membranes in the developing capillary stage. From the maturing glomerulus stage onward, the fused glomerular basement membrane (GBM) increased in thickness by excessive accumulation of the basement membrane material secreted from the epithelial cells. This accumulation was followed by overall loss of epithelial foot processes in the glomeruli. These findings indicate that the disease in ICGN mice is caused by some defect(s) in the GMB maturation process, which may be crucial for the generation of the glomerular permselectivity.