URINE 



485 



much accentuated. Casts have been classified according to their 

 microscopical characteristics as follows: (a) hyaline, (b) granular, (c) 

 epithelial, (d) blood, (e) fatty, (/) waxy, (g) pus. 



(a) Hyaline Casts. These are composed of a basic material which 

 is transparent, homogeneous, and very light in color (Fig. 148). 

 In fact, chiefly because of these physical properties, they are the 

 most difficult form of renal casts to detect under the microscope. 

 Frequently such casts are impregnated with deposits of various forms, 

 such as erythrocytes, epithelial cells, fat globules, etc., thus rendering 

 the form of the cast more plainly visible. Staining is often resorted to 



FIG. 148. HYALINE CASTS. 

 One cast is impregnated with four renal cells. 



in order to render the shape and character of the cast more easily 

 determined. Ordinary iodine solution (I in KI) may be used in this 

 connection; many of the aniline dyes are also in common use for this 

 purpose, e.g., gentian- violet, Bismarck-brown, methylene-blue, fuchsin, 

 and eosin. Generally, but not always, albumin is present in urine 

 containing hyaline casts. Hyaline casts are common to all kidney 

 disorders, but occur particularly in the earliest and recovering stages 

 of parenchymatous nephritis and interstitial nephritis. 



(b) Granular Casts. The common hyaline material is ordinarily the 

 basic substance of this form of cast. The granular material generally 

 consists of albumin, epithelial cells, fat, or disintegrated erythrocytes or 



