THE KIDNKY 



425 



pars radiata of the cortex. They contain straight portions of the urinif- 



erous tubules; these are continuous with the similar tuhules in the 



boundary zone of the medulla. These columns lie within the cortex and 



not, as their name might be taken to indicate, in the medulla. They 



are termed 'medullary rays' 



because of their peculiar rela- 



tion to the medulla, from 



which they extend outward in 



a radial direction. It would 



seem more proper to desig- 



nate them 'cortical rays.' 



That portion of the cortex 

 which invests the cortical 

 rays and which includes all 

 the remaining cortical por- 

 tions of the organ, consists of 

 extremely tortuous tubules, 

 and is characterized by the 

 presence of small globular 

 bodies, each of which con- 

 tains a tuft of capillary ves- 

 sels. These are the renal 

 corpuscles (Malpighian bod- 

 ies) which are characteristic 

 of the kidney. The portion 

 of the cortex in which they 

 occur includes the entire cor- 

 tical substance with the ex- 

 ception of the cortical rays, 



and is known as the renal a > P a P illal T zone > and b > boundary zone of 

 7 7 . ,, the medulla; c, cortex; /, apex of a renal 



labyrinth or pars convohita. pyramid; 2 , capsule; 3, tubules of the me- 



The labyrinth is divided dulla; 4, vasa rectae; 5, vascular arcades; 6, a 



into: (1) the renal columns, cortical ra y; 7 > labyrinth; 8, in terlobular ar- 



tery; 9, renal corpuscle; 10, 'cortex corticis. 

 already mentioned; (2) the (After Testut.) 



intercolumnar portions, or 



labyrinth proper, which includes that portion of the labyrinth which 

 invests the cortical rays, and which, in sections cut parallel to these 

 columns (longitudinal sections) appears as a portion of cortex inserted 

 between the adjacent rays; (3) a narrow bounJanj zone of the cortex, 

 'cortex corticis of Hyrtl, whifh is included between the lihroiis capsule 



FIG. 398. DIAGRAM OF THE STRUCTURE OF 

 THE KlDNEV - 



