THE UROGENITAL SYSTEM. 255 



IV. THE UROGENITAL SYSTEM. APPARATUS UROGENI- 



TALIS. 



i . The Excretory Organs. 



KIDNEY. REN (Figs. 108 and 109). 



The kidneys of the cat are compact (i.e., not tabulated) and 

 have the usual kidney or bean form. They lie in the abdomi- 

 nal cavity, one on either side of the vertebral column, against 

 the dorsal body wall, in the region between the third and fifth 

 lumbar vertebrae. The right kidney is one or two centimeters 

 farther craniad than the left, and the long axes of the two con- 

 verge craniad a little. Each is covered by peritoneum on 

 its ventral surface only (i.e., it is retroperitoneal). At the 

 border of the kidney, where the peritoneum passes from it to 

 the body wall, there is an accumulation of fat, which is most 

 abundant at the cranial end of the kidney. Within the peri- 

 toneal investment the kidney is enclosed in a special loose 

 fibrous covering, the capsule or tunica fibrosa, which is con- 

 tinuous with the fibrous coat of the ureter and pelvis. In the 

 middle of the median border of each kidney is a notch, the 

 hilus. It gives exit to the ureter (Fig. 108, c) and renal veins 



FIG. 108. LEFT KIDNEY, VENTRAL FIG. 109. MEDIAN LONGITUDI- 



SURFACE. NAL SECTION OF KlDNEY. 



Fig. 108. a, renal artery; b, renal vein; c, ureter. 



Fig. 109. a, medullary portion; b, cortical portion; c, papilla; d. pelvis; e, renal 

 artery; f, renal vein; if, ureter. 



(<$), and entrance to the renal artery (#). On the ventral sur- 

 face of the kidney within the capsule are seen grooves radiating 

 from the hilus. They contain blood-vessels. If the substance 

 of the kidney is sliced away parallel to the ventral surface for 

 some distance (Fig. 109), there is exposed a cavity, the sinus, 



