LECTURE XII. 



URINARY ORGANS AND MAMMARY GLANDS. 



Urinary organs are kidneys, ureters, bladder, urethra. 



Kidneys. — These important organs are situated in the sub- 

 kmibar regions, supported in place by large blood vessels and 

 connective tissue. They differ in shape, size and location, the 

 right one being larger, farther forward and more nearly round. 

 Each is covered by a fibrous capsule from which bundles of 

 connective tissue branch to penetrate the organ and form a frame- 

 work. 



FIG. 24. LENGTHWISE SECTION OF THE HORSE'S KIDNEY, 

 a, Cortical portion; b, medLillary portion; d, d, d, pthis; g, ureter. 



Internal structure. — On cutting open a kidney we may see 

 two distinct portions separated l)y a wavy line, and a cavity at 

 the root. The two portions are cortical (outside), medullary 

 (center). 



The cavity at the root, called pelvis, is merely the funnel 

 shaped origin of the ureter. 



The arterioles terminate and the urine tubules have their 

 origin in the cortical portion. These little urine tubes make up 

 a large part of the l)ulk of the kidney. Each tubule begins 

 somewheri' in the cortical portion in a little sac like cavity, with- 



