432 



THE URINARY SYSTEM 



which region only they occur. This portion of the tubule is remarkable 

 for the irregularity of its course, it being twisted and bent upon itself in 

 a most tortuous manner. Arising at the renal corpuscle, it at first passes 

 toward the surface of the organ, but soon turns about and runs toward 





FIG. 403. FROM THE CORTEX OF THE HUMAN KIDNEY, SHOWING A TRANSECTION 

 OF A CORTICAL RAY IN THE LOWER LEFT-HAND CORNER. 



a, glomerulus; 6, glomerular capsule; c, proximal convoluted tubule; d, collecting 

 tubule; e, ascending limb of Henle's tubule;/, spiral tubule; g, blood-vessel; h, distal 

 convoluted tubule. Hematoxylin. X 200. (After Schaper, from Stohr.) 



the medulla, at first with extreme convolutions, but later pursuing a 

 rather spiral course (spiral tubule). On reaching the border of the 

 medulla the tubule becomes sharply constricted and enters the medullary 

 boundary zone at the thin descending limb of Plenle's loop. 



