Chronic progressive nephropathy: functional, morphological, and morphometrical studies.

Some aspects of the functional, morphological, and morphometrical characteristics of chronic progressive nephropathy occurring in 18- to 26-month-old male rats and in 3-month-old control rats were studied. Rats with chronic progressive nephropathy were proteinuric and showed a slight increase in serum creatinine and no changes in blood pressure. The morphological changes were studied by light microscopy, high-resolution light microscopy, and electron microscopy. They showed focal and segmental or global glomerulosclerosis, the three types of atrophic tubules ("classic," "thyroid-like," and "endocrine") described by Nadasdy et al, as well as interstitial fibrosis with mononuclear cell infiltrates. On certain occasions, small vessels showed hyalinosis. Glomerular morphometrical studies showed a biphasic pattern in the glomeruli progressing toward obsolescence. Vascular morphometrical studies showed significant increase in media wall thickness and media cross-sectional area in the 18- to 26-month-old rats. These results support the hypothesis that changes in the vascular system are not of utmost importance in the pathogenesis of chronic progressive nephropathy, and that glomerular sequential changes seem to be of paramount significance in the progression of the disease.