THE KIDNEY 



425 



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

 erous tubules ; these are continuous with the similar tubules ki 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 rejial 

 labyrinth or pars convoluta. 

 The "labyrinth is divided 

 into: (1) the renal columns, 



FIG. 398. DIAGRAM OF THE STRUCTURE OF 

 THE KIDNEY. 



a, papillary zone, and 6, boundary zone of 

 the medulla; c, cortex; 1, apex of a renal 

 pyramid; 2, capsule; 3, tubules of the me- 

 dulla; 4) vasa rectse; 5, vascular arcades; 6, a 

 cortical ray; 7, labyrinth; 8, interlobular 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 boundary zone of the cortex, 

 ' cortex corticis' of Hyrtl, which is included between the fibrous capsule 



