THE KIDNEY 



191 



most difficult of all the tubuli uriniferi to demonstrate. The 

 section must be very thin, and even then they may be mistaken 

 for blood -capillaries. Their peculiar feature consists in the wavy 

 lumen, which is produced by the alternate disposition of the lining 

 cells.) 



d. Loops of Henle. (The loops will be recognized by the 

 curving of the tube. They are lined with short columnar cells, 



FIG. 120. MEDULLARY PORTION OF SPECIMEN SHOWN IN FIG. 118 (X400). 



A. Collecting tubule in L. S. 



B. Collecting tubule from above, showing attached bases of lining cells. 



C. Collecting tubule presenting different appearance of lining cells, according to mode of 



section. 



D. Ascending limb of Henle's loop. 



E. Same as last. The upper end of the tubule not sectioned. 



F. Descending limb of Henle's loop. Below may be seen the loop and ascending limb. 



G. Oblique section of large collecting tubule. 



H. Basal attached extremities of cells lining a large collecting tubule. 

 I. Intertubular capillaries. 



which are sharply brought out by the haematoxylin. On account 

 of their course, but few complete sections are seen.) 



e. Ascending limbs. (Conveniently traced from the loops.) 

 /. Intertubular blood-vessels. (Do not mistake tubules con- 



