560 THE URINARY ORGANS OF THE HORSE 
and blood-vessels. It is very scanty in the cortex, much more abundant in the medulla, in which 
it Increases In amount toward the pelvis. 
Vessels and Nerves.—The kidneys receive a large amount of blood through the 
renal arteries which come from the aorta.! Branches of these enter at the hilus and 
on the ventral surface of the gland, and reach the intermediate zone, where they 
form anastomotic arches (Arterize arciformes). From these arciform arteries 
branches pass into the cortex and medulla. The cortical branches (Arteri inter- 
lobulares) have in general a radial course between the cortical lobules, and give off 
short lateral branches, each of which ends as the afferent vessel (Vas afferens) of a 
renal corpuscle. The blood is carried from the glomerulus by a smaller efferent 
phe Artery of capsule 
Arched collecting Interlobular 
tubule ~~ CCAR) 
Straight collect- --- 
ing tubule 
Distal convo- ---- --- --=-€< 
luted tubule f 
Renal (Malpig- Ps 
hian) corpuscle 
Proximal convo- 
luted tubule 
Loop of Henle « 
Capillary net- 
work. Vas 
--~  afferens 
. Arteriola recta 
spuria 
Collecting tubule -4---------- 
Arteria arci- ___--4.----4 
formis H 
uf ~~~ Vena arciformis 
Large collecting 
tubule 
Papillary dict) sasa2s=- sso aae 
Fic, 502,—DiaAGRAMMATIC SCHEME OF URINIFEROUS TUBULES AND BLOOD-VESSELS OF KIDNEY. 
Drawn in part from the descriptions of Golubew (Bohm, Davidoff, and Huber). 
vessel, which breaks up immediately into capillaries which form networks around 
the tubules. The medullary branches descend in the pyramids, forming in them 
bundles of straight twigs (Arteriole rectze). The renal veins are large and thin- 
walled; they go to the posterior vena cava. In the superficial part of the cortex 
the veins form star-like figures (Venz stellate) by the convergence of several small 
radicles to a common trunk. The lymph-vessels form two networks, capsular or 
superficial, and parenchymatous or deep. On leaving the hilus they go to lymph 
glands in this vicinity which are known as the renal lymph glands. 
The nerves are derived from the renal plexus of the sympathetic, which en- 
laces the renal artery. 
1 The occurrence of accessory renal arteries is not at all rare. They may come from various 
branches of the aorta (e. g., posterior mesenteric, spermatic, circumflex iliac) and enter the posterior 
part of the gland. 
