TUBULI URINIFERI 



373 



several distinct curves and is lined with short columnar cells. The tube 

 next passes almost vertically downward toward the medulla, forming the 

 spiral tubule, still within the cortex of the kidney, which is of much the same 

 diameter. The loop of Henle, L, in the medulla, is a very narrow tube lined 

 with flattened nucleated cells. Passing vertically upward from the loop of 



LABYRINTH \MED.RAY\ LABYR. 



Pelvit 



FIG. 287. Scheme of Uriniferous Tubule and of the Blood- vessels of the Kidney, Showing Their 

 Relation to Each Other and to the Different Parts of the Kidney. G, Glomerulus; BC, Bowman's 

 capsule; TV, neck, PC, proximal convoluted tubule; S, spiral tubule; D, descending arm of Henle's 

 loop; L, Henle's loop; A, ascending arm of Henle's loop; IDC, distal convoluted tubule; AC, arched 

 tubule; SC, straight collecting tubule; ED, duct of Bellini; A, arcuate artery, and V, arcuate vein, 

 giving off interlobular vessels to corte.x and vasa recta to medulla; a, afferent vessel of glomer- 

 ulus; e, efferent vessel of glomerulus; c\ capillary network in cortical labyrinth; s, stellate veins; vr, 

 vasa recta and capillary network of medulla. (Pearsol.) 



Henle, the tubule varies somewhat in histological character, but the irregular 

 tubule and the distal convoluted tube, identical in all respects with the prox- 

 imal convoluted tube, are to be noted. The proximal convoluted tube 

 passes into the curved and straight collecting tubes, the latter running 

 vertically downward to the papillary layer, and, joining with other collecting 

 tubes, form larger ducts which finally open at the apex of the papilla. These 

 collecting tubes are lined with nucleated columnar or cubical cells. 



