The Urinogenital System. 195 



(capsula adiposa), and is also held in position by the peritoneum, 

 which is stretched across its ventral surface. 



1. By removing the peritoneum and adipose capsule from the 

 left kidney, the external features and vascular connections may be 

 made out as follows : 



(a) The general convexity of contour. 



(b) The renal hilus (hilus renalis) , a concavity of the medial 

 surface of the organ. 



(c) The ureter, or duct of the kidney, a white tube passing 

 backward from the hilus. , 



(d) The renal artery (a. renalis), arising from the abdominal 

 aorta and entering the kidney at the hilus. A branch of this 

 vessel, the suprarenolumbar artery (a. suprarenolum- 

 balis), passes to the body-wall in front of the kidney, giving 

 off a small suprarenal artery to the suprarenal gland. 



(e) The renal vein (v. renalis), leaving the kidney at the hilus, 

 and joining the inferior cava. 



2. Divide the kidney, beginning the incision at the hilus and 

 removing the ventral half (Fig. 50) . Examine the cut surface of the 

 dorsal half for the following: 



(a) The renal pelvis (pelvis renalis), formed by the expanded 

 funnel-like end of the ureter, which is fitted into the renal 

 hilus. A central cone of kidney substance, the renal 

 papilla (papilla renalis) projects into the pelvis. 



(b) The cortical substance (substantia corticalis) ; distinguish- 

 able as a narrow peripheral zone of the kidney substance. 



(c) The medullary s.ubstance (substantia medullaris), forming 

 the central and medial portion of the kidney, including the 

 renal papilla. It is distinguished by its radial striations. 



(d) The fibrous coat (tunica fibrosa) of the kidney may be 

 stripped from the surface. 



In the rabbit the kidney is not lobulated. Hence there is a single renal 

 papilla, and the division of the kidney substance into renal pyramids is imper- 

 fectly expressed. The medullary substance, however, possesses a slightly divided 

 margin. 



The cortical substance is of darker coloration in the natural condition, but 

 in embalmed animals the color features are usually reversed. 



