MORBID ANATOMY - CHRONIC PRODUCTIVE OR DIFFUSE NEPHRITIS WITH Gross Appearance of the Kidney . —There is considerable variety in the gross appearance of the kidneys. The types which I have seen most frequently are as follows: 1. Large white kidneys, weighing together sixteen ounces or more, the capsule adherent or not, the surface smooth or nodular, the cor tex thick and white, the pyramids large and red.
2. Large mottled kidneys. These resemble the large white kid net's in every respect except that the cortex, instead of being white, is mottled in a variety of ways with white, yellow, red, and gray.
3. Kidneys which resemble types one and two, but are not en larged, the kidneys together not weighing over nine ounces.
The majority of the kidneys in chronic nephritis follow these three types.
4. Small kidneys, weighing together not more than five ounces, the capsules adherent or not, the surfaces nodular, the cortex thin, atro phied, white, the pyramids rather large and red. These kidneys be long to persons who have had symptoms of kidney disease for many years, with periods of apparent recovery.
5. Kidneys which have the ordinary appearance and consistence of the chronic congestion due to heart disease, but in addition the capsules are adherent and the surfaces finely nodular.
6. Kidneys of different sizes—large, medium-sized, and small,with adherent capsules and nodular surfaces. The cortex is gray, or gray mottled with red. The kidneys do not look at all like the large white kidneys. This is a type of frequent occurrence.
7. Kidneys which in their size, color, and general appearance are hardly to be distinguished from normal kidneys, except that their capsules are adherent.
8. Kidneys of small size, weighing together not more than four ounces, with adherent capsules. The cortex is atrophied, red, and irregular. These kidneys are found in persons who have given symp toms of renal disease for a number of years.
It might naturally be supposed that such marked differences in the gross appearance of the kidneys would correspond to equally marked differences in the clinical histories and minute lesions.
This, however, is not the case. The clinical histories are practically interchangeable, and the minute lesions are essentially the same.
.Microscopical Appearances.—If we make vertical sections of the cortex of all these kidneys, no matter what their size or color, we get with a low magnifying power the same general picture. Instead of the uniform and orderly arrangement of tubes and glomeruli which we see in the normal kidney, the tubes seem to be obliterated in some places and dilated in others. There is a growth of fibro-cellular tissue in regular wedges, in irregular patches, or diffuse between the tubules.
If we examine the different constituents of the kidney in detail we find : The tubes are in some places of normal size, in some places atro phied, in some places dilated. The atrophied tubes are in the patches of new connective tissue. The dilated tubes are not very large, nor do they form cysts.
The epithelium of the tubes is in some places merely flattened.
These tubes are empty, or contain coagulated matter, casts, and red and white blood-cells. In other tubes the epithelium is more or less swollen, sometimes so much so as to completely fill the tubes. In still other tubes the epithelial cells are swollen, their reticulum is very coarse with large meshes, and they are infiltrated with fat. The kidneys vary as to which of these changes in epithelium pre dominates, but all of them may be found in the same kidney.
The new connective tissue is in the form of wedge-shaped masses in the cortex which follow the line of the straight arteries and veins, or it is in irregular masses, or it is arranged diffusely so as to sepa rate the tubes from each other. The longer the nephritis lasts, the greater is the quantity of new connective tissue. The relative pro portion of basement substance and cells and the density of the base ment substance vary in the different kidneys. The new tissue is well supplied with blood-vessels.