444 



THE URINARY SYSTEM 



The yen u he rcct;i i are peculiar in their typically straight course, 

 and in the J'ael that the cells of their endothelium are extremely long- 

 so long indeed, as frequently to present a somewhat fibrous appearance, 

 the elongated axis of the cell being parallel to the long axis of the vessel. 

 The capsule of the kidney is supplied by branches of the lumbar, 

 phrenic, and suprarenal arteries, which form a rich, capillary plexus. 



These vessels anastomose with the terminal 

 branches of the interlobular arteries of the 

 kidney in the manner above described a 

 fact which acquires surgical importance from 

 its relation to the establishment of a collat- 

 eral circulation. 



The table on page 443 may be useful as a 

 resume of the more important paths in the 

 course of the renal circulation, in it the 

 names of the several vessels are arranged in 

 order and the arrows indicate the direction 

 of the blood current. 



Lymphatics. The renal lymphatics con- 

 sist of a superficial set which forms plexuses 

 in the perirenal fat and deeper layers of the 

 capsule, and a deep set which supplies the 

 parenchyma of the organ. These two sets of 

 lymphatic vessels are in communication by 



IN A CONVOLUTED TUBULE frequent anastomoses. The vessels of the 

 OF THE FROG'S KIDNEY. superficial set convey their lymph to the 



neighboring lymph glands of the lumbar 



FIG. 409. NERVE ENDINGS 



a, nerve fiber; b, blood-ves- 

 sel; c, secreting epithelium. 

 Methylene blue; cochineal. 

 Very highly magnified. (Af- 

 ter von Smirnow.) 



region. 



The deep renal lymphatics accompany 

 the arteries and veins throughout their 

 course. They form narrow cleftlike vessels 



of irregular caliber in the scanty interstitial tissue between the urinifer- 

 ous tubules of both cortex and medulla. These vessels are relatively few 

 in number. They converge to the hilum of the organ where they pass to 

 the nearby lymphatic glands. 



Nerves. The nerves of the kidney include both medullated and 

 non-medulla led libers. The sympathetic fibers form a ganglionated 

 plexus in the connective tissue about the renal pelvis. From this plexus 

 fibers are distributed to the blood-vessels of the capsule and to the 

 parenchyma of the organ. The latter accompany the blood-vessels, dis- 



