440 



THE UEINAEY SYSTEM 



The following tabular resume may be of service by emphasizing the 

 more important peculiarities of the several portions of the uriniferous 

 tubule. 



RENAL BLOOD-VESSELS, LYMPHATICS AND NERVES 



Blood Supply. The kidney receives its blood supply from the renal 

 artery, which, as it enters the hilum, divides into two sets of principal 

 branches, of which the ventral set supply three-fourths, the dorsal set 

 one-fourth of the renal substance. These principal branches, the arterice 

 proprice renales, or interlobar arteries, are embedded in the connective 

 tissue of the sinus and follow the walls of the infundibula and calyces, 

 upon which they lie, thus reaching the renal columns between the renal 

 calyces. Here they enter the cortical substances and divide, each branch 

 passing in a curved or arched manner beneath the base of the adjacent 

 pyramids. These vessels form an incomplete arterial arcade (arciform 

 artery) which lies in the margin of the cortex at the outer border of the 

 medullary boundary zone. 



From the arterial arcade, branches are given to the medullary tissue 

 of the pyramids on the one hand, and on the other to the cortical sub- 

 stance, Those branches which enter the medulla are slender vessels which 



