Senile changes of the renal cortex [an E/M study]

ABSTRACT

In order to clarify the ultrastructural changes in the kidney due to senility, 14 adult male albino rats were used, where they were divided into two groups. The first group consisted of 8 senile rats aged 1 - 1.5 years, whereas the other 6 animals were aged 5 - 6 months and served as a comparative second group. The renal corpuscles of the senile rats exhibited an irregularity both in thickness and arrangement of the feet processes of their podocytes, where they appeared attenuated in some sites and fused together elsewhere. The glomerular basement membrane was thickened, mainly due to the widening of its lamina densa. These glomerular changes might be an indication to the affection of the filtration capacity of the senile kidneys. The senile renal tubular epithelial cells were characterized by their smaller, more electron dense mitochondria, irregularity and increased thickness of their basement membranes. These characters might explain the decreased reabsorptive and secretory functions of the renal tubules described by many authors. The senile proximal convoluted tubules showed an increased number of both in the pinocytotic vesicles and lysosomes which might be related to the possible increased rate of passage of the protein macromolecules through the senile leaky glomerular filtration barrier. The cortical interstitium of the senile kidneys contained hyperactive fibroblasts, which might indicate the early interstitial renal fibrosis. The basement membrane of the endothelium of the small cortical vessels was thickened and lost its elastic tissue content. This could be a sign of early atherosclerotic changes that might be the trigger for the later rise of blood pressure in old age