Classification of the anatomic changes in what appears clinically to be chronic nephritis is made difficult by the variety and peculiarity of the anatomic lesions found in the kidneys. From a purely morphologic point of view, the renal changes can be divided into two main groups: (1) inflammatory changes involving primarily the glomeruli or the tubular parenchyma or both, and (2) changes involving primarily the vascular apparatus, with other changes occurring apparently secondarily. While the former condition, the nephritis sensu strictu, is easy to understand, the greatest difficulties are met with in the interpretation of the vascular renal disease.
According to the latest anatomic work in this line, vascular changes of the kidneys are to be classified, according to the size of the arteries involved, into arteriosclerotic and arteriolosclerotic changes. In the first, large discrete foci of atrophy are found with no impairment of renal function. In the arteriolosclerotic type,