166 



THE URINARY ORGANS. 



FIG. 68. 



Course of bloodvessels in the 

 kidney (Ludwig). a, inter- 

 lobular artery; b, inter- 

 lobularvein;c, Malpighian 

 body, with afferent and 

 efferent vessels and glom- 

 erulus; d. stellate vein; 

 e, arterise rectrc ; f, venae 

 rectae ; g, capillaries about 

 mouths of outlet-ducts. 



ing the sinus. They give off twigs 

 which supply this region and divide 

 into a number of branches, the arterice 

 and venae proprice renales, which pass 

 outward in the columnse Bertini, be- 

 tween the Malpighian pyramids. 



On reaching the bases of these pyra- 

 mids they divide into the arcuate ar- 

 teries and veins, which follow the 

 boundary between the cortical and 

 medullary regions and, anastomosing 

 with one another, form complete ar- 

 terial and venous arches over the bases 

 of the Malpighian pyramids. From 

 these arches two sets of small vessels 

 are given off, one the interlobular, pass- 

 ing radially outward into the cortex ; 

 the other, the vasa recta, converging 

 inward to supply the medulla. 



The interlobular arteries, 1 or cortical 

 arteries, are small straight branches 

 from the arterial arches passing radially 

 outward in the interpyramidal cortical 

 regions, midway between the pyramids 

 of Ferrein. They give off a small 

 twig to each of the Malpighian bodies 

 along their course, which enters the 

 glomerulus as its afferent vessel. In 

 the glomerulus the afferent vessel 

 breaks up into a capillary tuft; the 

 capillaries then reunite to form a single 

 efferent vessel leaving the glomerulus. 

 These efferent vessels then mostly 



1 Each pyramid of Ferrein, with the tributary 

 interpyramidal tubules in its vicinity, may be 

 regarded as a distinct section or physiological 

 lobule of the renal cortex, though they are not 

 marked off' from one another by definite bound- 

 aries into distinct lobules. The cortical arteries 

 pass between these sections or lobules, whence 

 the term interlobular. 



