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 (Arterise arciformes). From these arciform arteries 

 branches pass into the cortex and medulla. The cortical branches (Arterise 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 



Arched collecting 

 tubule 

 Straight collect- 

 ing tubule 

 Distal convo- 

 luted tubule 

 Renal (Malpig- 

 hian) corpuscle 

 Proximal convo- 

 luted tubule 

 Loop of Henle 



Collecting tubule 



Arteria ard- 

 formis 



Large collecting 

 tubule 



Papillary duct 



Artery of capsule 



Interlobular 

 artery 



Capillary net- 

 work. Vas 

 afferens 



Arteriola recta 

 spuria 



. Glomerulus 



■~ Vena arciformis 



Fig. 



302. — Diagrammatic Si'heme 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 (Arteriolse rectse). 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 (Venae stellatse) 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. 



