332 THE ORGANS 



immediately splits up into a number of branches — the interlobar 

 arteries (Fig. 230, g). These give off twigs to the calyces and to the 

 capsule, then without further branching pass between the papillse 

 through the medulla to the junction of medulla and cortex. Here 

 they bend sharply at right angles and following the boundary line 

 between cortex and medulla, form a series of arches, the arterice 

 arciformes or arcuate arteries (Fig. 230, d). From the arcuate arteries 

 two sets of vessels arise, one supplying the cortex, the other the me- 

 dulla (Figs. 223 and 230). 



d < 







<^ "^ ^: 



I 





b c 



Fig. 229 — Cross Section through Medulla of Human Kidney. X465. (Technic 2, 

 P- 33^-) a, Capillaries; b, collecting tubule; c, ascending arms of Henle's loops; d,ide- 

 scending arms of Henle's loops. 



The arteries to the cortex spring from the outer (Fig. 230, b) sides of 

 the arterial arches, and as interlobular arteries pursue a quite straight 

 course through the cortical pyramids toward the surface, about mid- 

 way between adjacent medullary rays. From each interlobular artery 

 are given off numerous short lateral branches, each one of which 

 passes to a Malpighian body. Entering a Malpighian body as its 

 afferent vessel, the artery breaks up into a number of small arterioles, 

 which in turn give rise to the groups of capillaries which form the 



