PATITOLOGY. In acute congestion, the kidneys are swollen and darker than normal, the vesstdd, containing an increased amount of blood. There may be flattening of the tubules from pressure and exudation into them. In acute degeneration the kidney is usually somewhat enlarged; it may be congested, and the cortical portion is often swollen and pale. The cells of the kidney tu bules are swollen and granular, and show vari ous stages of disintegration up to complete de struction of the cells. lVithin the tubules are fat-globules. coagulated albumen, and granular matter, resulting front degeneration of the epi thelium. In acute exudative inflammation the condition of the kidneys varies greatly. There may be simply conge.tion, with inflammatory products in the tubules. The kidney may he enlarged and congested, the cortex thick, pale, and wet. The epithelium of the tubules is apt to be swollen or flattened by the exudate, dis integrated, and there are collections of white blood-cells scattered throughout the cortex. In the lumina of the tubules are masses of coagu lated albumen, casts (either clear or contain ing red or white blood-cells), and the results of cellular disintegration. In the glomeruli of the kidneys there is a thickening of the capsule epithelium and of the cells lining the capillaries, so that the outlines of the capillaries disappear. There is often an accumulation of coagulated albumen and detritus within the cavity of the glomerulus. In acute productive inflammation the kidneys are increased in size, the surface smooth- and the non-adherent. An acute exudative inflammation such as has just been described is usually present. hut added to this is an increase in the connective-tissue elements of the kidney, with consequent atrophy of the tubules. There may be extreme proliferation of the capsule-yells of the glomeruli. The kidneys remain permanently damaged organs.
In chronic congestion the kidney is somewhat enlarged, heavy, hard, of dark-red color, the surface smooth, and the capsule non-adherent. The epithelial cells of the tubules may be swol len, and in the glomeruli the capillaries are dis tended, and there is more or less thickening of their walls. In chronic degeneration, due to
heart-disease, the kidneys are usually large and white, the cortex being thiekened. The epi thelium of the tubules is swollen and granular, and in the glomeruli the capsule-cells are dis tended and their walls thickened. In the de generation which occurs in wasting diseases, the changes in the glomeruli are apt to be ab sent, while in senile degeneration the kidney may he either large and white, or small, red, and atrophied, with changes in the epithelium of the tubules, but no change in the glomeruli. In chronic diffuse inflammation with exudation, or chronie parenchymatous inflammation, the nee of the kidney varies greatly. It is usually enlarged, more rarely it is of normal size or small. Its surface may be smooth or nodular. The cortex may be thickened and white, or mottled. The epithelium of the tu bules may be flattened by exudate, or swollen and granular. Some tubules are of normal size, others are dilated, while still others are compressed by the new connective tissue. With in the lumina are coagulated albumen, disin tegrated epithelimn, and red and white blood cells. In the glomeruli there is an increase in the connective-tissue elements with atrophy, and the capillaries may show waxy degenera tion. There is an increase in the interstitial connective tissue of the kidney, but it is not extensive. The arteries often show increased thickness of walls. In chronic diffuse inflamma tion, without exudation, or cirrhosis of the kid ney, the kidney is apt to be small, its surface rough, and its capsule adherent. Rarely the kidneys are large. The increase in connective tissue is the most marked feature, and is often extreme. Dependent upon or determining this increase in connective tissue is atrophy of the tubules and of the glomeruli. The tubules are sometimes greatly swollen, and form casts. The blood-vessel walls are usually thickened, and the capillaries of the glomeruli may show waxy changes. See ALBUM INURI A and KIDNEY. Con sult Osier, Principles and Practice of Medicine (New York, 1901).