2 66 



NORMAL HISTOLOGY AND ORGANOGRAPHY. 



and the mould is then called an epithelial cast. The 

 cells may have decomposed, when it becomes a 

 granular cast. Hyaline casts often show granula- 

 tions and are then also called granular casts. Finally, 

 fatty degenerations may appear and form fatty 

 casts. The recognition and identification of casts 

 form an important subject in clinical analysis. If 

 small pieces of kidney are treated with strong hydro- 

 chloric acid and the detritus thus produced be ex- 

 amined in gly- 

 cerin, under a low 

 magnification, 

 many pieces of 

 the uriniferous 

 tubules are read- 

 ily observed. 

 These pieces are 

 practically iden- 

 tical with the epi- 

 thelial and gran- 

 ular casts of the 

 diseased kidney. 

 Blood-vessels. The kidneys are highly vascular 

 and receive a large amount of blood in proportion to 

 their size. The renal artery and renal vein pass 

 through the hilum, the artery between the vein and 

 ureter. In the renal fissure the artery breaks up 

 into four or five branches which lie external to the 

 pelvis of the ureter. These branches pass directly 

 to the columns of Bertini, where they break up into 

 smaller vessels and rise to the level of the Mal- 

 pighian pyramids. At this level they pass across 

 the pyramids, between the latter and the cortex, 



Capillary. 



Fig. 202. Section of a portion of a kidney 

 medulla. 



