THE UROGENITAL SYSTEM 



417 



Renal Tubules. The structure of the kidney as just described is 

 determined by the arrangement of the kidney tubules, which are the 

 functional units of the kidney. In the cortex, the renal tubules are 

 convoluted and connected with knots of blood capillaries, the glomeruli. 

 The pyramids, on the other hand, consist chiefly of straight collecting 



Renal corpuscle. Convoluted tubules. Cortical ray. 



Interlobular vein. 



/ 



Henle's loop. Arciform vein. Arciform vein. 



Fig. 342. — Part of a radial section of a human kidney. At x a renal corpuscle has 

 dropped out. X5. (From Bremer's "Text Book of Histology.") 



tubules, which open into the renal pelvis by numerous apertures lying 

 at the ends of the papillae. 



Each renal tubule begins in a spherical capsule surrounding a glomeru- 

 lus, the combined structure being known as a renal corpuscle. The 

 swollen termination of a tubule is a Bowman's capsule. The portion 

 of the tubule adjacent to the corpuscle is convoluted and thickened, and 

 is known as the proximal convoluted part of the tubule. Passing into 

 one of the pyramids, the tubule becomes slender and straight, and is 



