An Electron Microscopic Study of Small Arteries and Arterioles in the Normal Human Kidney

Abstract

Electron microscopy of biopsy specimens from the renal cortex of 7 normal subjects showed that the small vessels could be divided into three groups. In the lobular artery and the first portion of the vas afferens there was a well-defined internal elastic lamina and a tunica media with one or more layers of typical smooth muscle cells. The juxtaglomerular part of the vas afferens was characterized by loss of internal elastic lamina and conversion of the muscle cells in the direction of the epitheloid form, with many granules. There was likewise no internal elastic lamina in the vas efferens, and its muscle cells contained only few myofilaments, but no characteristic granules. The ultrastructure of endothelium, muscle cells and interstitial tissue otherwise showed no features not described previously in animal tissue. The possibility of post-biopsy tissue changes is mentioned, and a short discussion is provided of the relationship between ultrastructure and function.