THE METANEPIIROS 



201 



the elaboration of urine, consists of those ])arts from Bowman's 

 capsule through the distal convoluted portion and may he called 

 the ne])hron. The main function of the excretory tubule is to 

 conduct urine from the secretory tubule, or nephron, to the pelvis. 



(Fig. 12(i.) 



Connecting tubiiU 



Distal convoluted 

 tubule 



Renal corpuscle 

 Proximal convoluted 

 tubule 



ijapsule 



Afferent arteriole 



Efferent arteriole 



Renal corpu,icle 



Interlobular vein 

 Interlobular artery 



Arched arteri/ 

 Arched vein 



^^^_^ „ ,— , , . ^ Interlobar vein 



Descending limb 



II I \ 11 "AV)M\\\ Ai^r-;vlr I'/fi^ 



^_ ^ ^^ Interlobar artery 



Ascending limb " ' " ' " ^^ > -> " n -^ , h , 



Collecting duct 

 Loop 



Papilla 

 Fig. 126. — Diagram of the iirinifproiis anfl vasfular system of a manmialian kidney. 



Blood Supply of the Kidney. — The renal artery and renal vein 

 divide into trunks, of which the greater number pass over the 

 front of the pelvis in man but ventrally in quadruped mammals. 

 Branches of these, known as interlobar arteries and veins (cohnnns 

 of Bertini) extend between adjacent pyramids to the boiuidary 

 between cortex and medulla. There, as arcuate arteries and veins, 

 they curve at right angles to lie between the cortex and medulla. 

 From the arcuate arteries, small vessels (interlobular arteries) extend 

 radially toward the cortex. From each interlobular artery a number 

 of afferent glomerular arterioles originate, one to each renal cor- 

 puscle. Each efferent glomerular arteriole forms a capillary net- 

 work in the cortex surrounding the con^'oluted tubule of that 



