PELVIS OF THE KIDNEY AND URETER 193 



variations in size and in the number of granules, dependent on 

 the state of secretion. 



DIAGRAM SHOWING DISTRIBUTION OP TUBULES (AFTER PIERSOL) 



CORTEX. 

 Labyrinth. Medullary Ray. 



Malpighian bodies. Spiral tubules. 



Necks of the tubules. Ascending limbs of loops of 



Proximal convoluted tubules. Henle. 



Irregular tubules. Collecting tubules. 



Distal convoluted tubules. 



Collecting tubules. 



Loops of Henle. 



Descending limbs. 



V MEDULLA. 

 Ascending limbs. 



Collecting tubules. 



PELVIS OF THE KIDNEY AND URETER 



The coats of the ureter are three in number mucous, muscu- 

 lar, and fibrous. The muscle is unstriated, and is divided into 

 inner longitudinal and outer circular layers. The pelvis of 

 the kidney, and the calyces and infundibula present a similar 

 structure. The circular muscular fibers are numerous around the 

 papillae, and form a kind of sphincter. 



Obtain the ureter of a human subject, if possible. Fix the fresh ureter 

 with alcohol or Miiller's fluid. Imbed in celloidin or paraffin. Cut thin sec- 

 tions, stain with hsematoxylin and eosin, and mount as usual. 



OBSERVE : 

 (L.) 



1. The relative thickness of the epithelium. 



2. The narrow mucosa. 



3. The internal longitudinal muscular layer. 



4. The bundles of the external circular muscular layer. 



5. The arteries between the muscular bundles. 



6. Adipose tissue, more or less abundant in the loose cellular 

 tissue surrounding these canals. (This element will afford a 

 prominent feature of the section of the pelvis of the kidney, while 

 the muscular tissue will be seen to a limited extent only.) 



(H.) Fig. 122. 



7. The epithelium, (a) That it is of the thin, stratified squa- 

 mous type known as transitional. >(&) The broad basal attach- 

 ed 



