NORMAL HISTOLOGY. 



131 



CHAPTER XIX. 



THE URINARY TRACT. 



The organs of the urinary tract are the kidney, ureters, bladder, 

 and urethra. Their tissues are derived from the epiderm and meso- 

 derm. The nervous supply is obtained from the cerebro-spinal and 

 s}onpathetic systems. 



THE KIDNEY. 



The kidney is one of the parenchyinatous organs of the body, il- 

 lustrating a compound tubular gland and functioning as an organ 

 of excretion. The urine is secreted from the blood in the Mal- 

 pighian bodies and uriniferous tubules, and contains the products 

 of destructive metabolism. 



OUTLINE OF THE KIDNEY. 



Cortex 



Medulla. 



Sinus . . 



Tubules. 



Hilum. 

 Pelvis. 

 Calices. 



Papilla. 



( Capsule of Bowman. 

 1 Glomerulus. 



Neck. 



Lumen. 



Proximal convoluted tubule. 



Spiral tubule. 



Descending limb of Henle's 



loop. 



Henle's loop. 

 Ascending limb of Henle's 



loop. 



Irregular tubule. 

 Distal convoluted tubule. 

 Arched collecting tubule. 

 Straight collecting tubule. 

 Excretory duct, or tube of 



Bellini. 



The outside investment of the kidney is a capsule of fibrous tis- 

 sue, within which is a thin layer of smooth muscle. The cortex of 



