ORGANIZED SEDIMENTS. 



505 



derived from the collecting tubules of the kidney; while if they are thinner and 

 tortuous, their source is suspected to be the convoluted tubules. 



^ Various kinds of tube-casts can be distinguished: i. Epithelial casts (Fig. 165), 

 which consist of coherent and desquamated cells of the urinary tubules. They 

 indicate that no profound change has as yet taken place within the kidney, but 

 that, as in catarrhal inflammatory states of mucous membranes, the epithelial 

 cells are in process of desquamation. 2. Hyaline tube-casts (Fig. 171) are com- 

 pletely homogeneous and transparent. They are most readily demonstrated by 

 addition of a solution of iodin to the preparation. They are generally long and 

 narrow; occasionally, they present fine disseminated points, or fat-granules (finely 

 granular tube-casts, Fig. 169). They appear not to be derived from a transud.a- 

 tion from the blood, but as a result of the secretory activity of the epithelial 



FTG. 166. Blood-casts. 



FIG. 167. Casts of Leukocytes 

 (after v. Jaksch). 



FIG. 168. Acid Sodium Urate in 

 the Form of Tube-casts. 



FIG. 169. Finely Granular Tube- 

 casts. 



FIG. 170. Coarsely Granular 

 Tube-casts (after v. Jaksch) 



FIG. 171. a. Hyaline tube-cast: 

 b, hyaline tube-cast with 

 leukocytes; c, hyaline tube- 

 cast with renal" epithelium 

 (after v. Jaksch). 



cells of the urinary tubules. 3. Darkly granular tube-casts (Fig. 170), brownish 

 yellow, opaque, and consisting wholly of a granular mass, are usually somewhat 

 wider than hyaline tube-casts. Marked variations of the latter occur. Not 

 rarely, they exhibit fattily degenerated or atrophic epithelial cells of the urinary 

 tubules. 4. Amyloid tube-casts occur in cases of amyloid degeneration of the 

 kidneys. They have a waxy luster, are completely homogeneous (Fig. 171, u) 

 and yield, with sulphuric acid and solution of iodin, the blue color of amyloid 

 reaction. 5. Blood-casts, consisting entirely of coagulated blood, with distinct 

 blood-corpuscles, occur in association with capillary hemorrhage into the tissue 

 of the kidney (Fig. 166). These are allied to the casts found in connection with 

 hemoglobinuria ; as, for instance, after transfusion of heterogeneous blood. They 

 consist of hemoglobin or of its globulin tinged with hematin. The tube-casts 

 stained yellow that have been observed in conjunction with icterus probably also 

 result from the albumin of dissolved blood-corpuscles. Urine containing tube- 

 casts is always albuminous. 



