1>1S MICROSCOPIC A3 ATOMY OF THE ORGANS. 



of the two poles of the kidney is derived from the main artery. 

 Single arteries run to each pole and break up into three 

 branches : a posterior, an anterior, and a median branch. 

 Between these large arteries there is no anastomosis ; and it 

 \\ill be seen that at one place between the anterior and pos- 

 terior arterial fields there is a comparatively non-vascular zone, 

 marked by the dotted line in Fig. 171. Brodel has pointed 

 out also the surgical importance of this fact. 



The branches of these arteries run to the kidney substance 

 between the pyramids as the interlobar arteries. At the 

 boundary between the medulla and cortex these bend over and 

 run for a short distance parallel to the surface of the kidney 



FIG. 169. 



Glomerulus from an injected human kidney, showing vas efferens and vas afferens. ' K0. 



(Figs. 165 and 170). In this way an arterial arch is formed, 

 made up of the arcuate arteries. From the convex side of 

 these arteries small branches proceed radially toward the kid- 

 ney surface. These are the so-called interlobular arteries. 

 They give off in all directions lateral twigs, which carry blood 

 to the Malpighian corpuscles (Fig. 165). These are the vasa 

 afferentia, which enter the capsules of Bowman and break up 

 into many branches to form the glomerulus (see above). The 

 blood is carried away from each glomerulus through the vas 

 efferens. Many vasa efferentia together break up to form a 

 capillary network in the region of the medullary rays. The 

 tubules of the medullary rays and the tubuli contort! lie in the 



